PREFINAL: IMMUNE SYSTEM AND LYMPHOID ORGANS Flashcards
1
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IMMUNE SYSTEM & LYMPHOID ORGANS
- Consists of 2 semi-independent parts:
A
Lymphatic vessels
Lymphoid tissues & organs
2
Q
Lymphoid tissues & organs 2 types
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Primary Lymphoid Organs
Secondary Lymphoid Organs
3
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B lymphocytes and T lymphocytes
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Primary Lymphoid Organs
4
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Spleen, Lymph nodes, and Mucosal-associated lymphoid tissues (MALT)
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Secondary Lymphoid Organs
5
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o Transport fluids back to the blood.
o play essential roles in body defense and disease resistance.
o Provides defense or immunity against foreign antigens inside the body.
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IMMUNE SYSTEM & LYMPHOID ORGANS
6
Q
Russian scientist who discovered and observed phagocytosis (cells
that eat cells) under the microscope.
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ELLIE METCHNIKOFF
7
Q
serum proteins produced by certain lymphocytes when exposed to a certain substance.
A
ANTIBODIES
8
Q
PRIMARY LYMPHOID ORGANS:
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Bone Marrow
Thymus
9
Q
One of the largest tissues in the body and fills the core of all long flat bones.
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Bone Marrow
10
Q
Main source of HSC (erythrocytes, granulocytes, monocytes,
platelets, and lymphocytes)
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bone Marrow
11
Q
Small, flat, bilobed organ found in the thorax, or chest cavity, right
below the thyroid gland and overlying the heart.
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Thymus
12
Q
Thymus weight by puberty?
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30 to 40 g
13
Q
Produces enough young t lymphocytes early in life.
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Thymus
14
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Maturation of T cells:
A
3 weeks
15
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Mature T cells released from the
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medulla
16
Q
Functions at peak levels only during ________ & produces hormones (like thymosin) to program lymphocytes.
A
childhood
17
Q
form in the thymus upon interacting with dendritic cells presenting self-antigens in a process promoted by cytokines from thymic epithelial cell (TEC) aggregates called Hassall
corpuscles, found only in the thymic medulla.
A
Regulatory T cells
18
Q
After maturation of T cells, they make their way to secondary lymphoid
organs.
- Main contact with foreign antigens takes place.
A
SECONDARY LYMPHOID ORGANS
19
Q
largest lymphatic vessel in the body.
• Collects most of the body’s lymph fluid and empties it into the left subclavian vein.
A
THORACIC DUCT
20
Q
Making of lymphocytes which occurs in secondary lymphoid organs and
is dependent on antigenic stimulation.
A
LYMPHOPOESIS
21
Q
Largest secondary lymphoid organ.
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spleen
22
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Located in the upper-left quadrant of the abdomen below the diaphragm.
A
spleen
23
Q
Large discriminating filler that removes old and damaged cells and foreign antigens from the blood.
A
spleen
24
Q
Spleen receives blood vol. _______ and allows lymphocytes and macrophages to constantly survey for infectious agents
A
approx. 350 mL/minute
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lined by unusual endothelial cells called “stave cells”
SPLENIC SINUSOIDS
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elongated and aligned parallel to blood flow with open slits between the cells.
STAVE CELLS
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2 types of spleen
red pulp
white pulp
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Filters blood, removes defective erythrocytes, and recycles hemoglobin iron, consists of splenic cords with macrophages and blood cells of all kinds and splenic sinusoids.
red pulp
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Blood flow in red pulp is either a
close circulation or open circulation
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CLOSE CIRCULATION, moving from
capillaries into the
venous sinusoids
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OPEN CIRCULATION, capillaries
open directly into
splenic cords
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only 20% of the spleen, is a secondary lymphoid tissue associated with small central arterioles that are also enclosed by PALS (periarteriolar lymphoid sheaths) of T cells.
white pulp
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contains mainly T-cells.
Periarteriolar lymphoid sheath (PALS)
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contain B cells that are not yet stimulated by antigens.
Primary follicles
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Kidney-shaped, <1inch long & covered by a capsule of dense connective
tissue. Located along lymphatic ducts, numerous near joints, and where the arms and legs join the body.
LYMPH NODES
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o Provide the ideal environment for contact with foreign antigens that
penetrate the tissues.
o Filtration of interstitial fluid from around cells in the tissues,
it allows contact between lymphocytes and foreign antigens
from the tissues.
o Filters lymph and provides a site for B-cell activation and
differentiation to antibody-secreting plasma cells.
o Provide the ideal environment for contact with foreign
antigens that penetrate the tissues
LYMPH NODES
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fluid that surrounds cells & tissues.
INTERSTITIAL FLUID
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filtrate of blood and arises from the passage of water and into the interstitial spaces between cells.
LYMPH FLUID
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2 types of lymphatic vessels
lymph capillaries
lymphatic vessels
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Walls overlap to form flap-like mini valves & fluid leaks
into them.
▪ Higher pressure on the inside closes mini valves.
lymph capillaries
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Collects lymph from lymph capillaries & carries lymph to
& away from lymph nodes.
• Returns fluid to circulatory veins near the heart.
Lymphatic collecting vessels/Lymphatic vessels
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ideal location for phagocytosis
sinuses
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consist of antigen-stimulated proliferating B cells
secondary follicles
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transformation of B cells takes place.
Germinal center
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outer part, contains follicles (collections of lymphocytes).
cortex
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location of T-cells in lymph nodes.
paracortex
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inner part, contains phagocytic macrophages.
medulla
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defense cells
macrophages
lymphocytes
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engulf and destroy foreign substances.
macrophages
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provide immune response to antigens.
lymphocytes
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- Found in gastrointestinal, respiratory, and urogenital tracts. - One of the largest lymphoid organs (70%) - Ex. Tonsils, appendix, and urogenital tracts, and Peyer patches (a specialized type of MALT located at lower ileum of t h e intestinal tract)
MUCOSA-ASSOCIATED LYMPHATIC TISSUE (MALT)
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- Found in gastrointestinal, respiratory, and urogenital tracts. - One of the largest lymphoid organs (70%) - Ex. Tonsils, appendix, and urogenital tracts, and Peyer patches (a specialized type of MALT located at lower ileum of t h e intestinal tract)
MUCOSA-ASSOCIATED LYMPHATIC TISSUE (MALT)
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Location: Small masses of lymphoid tissue around the pharynx
▪ Trap & remove bacteria & other foreign materials
Tonsil
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located posteriorly on the soft palate, are covered by stratified squamous epithelium.
▪ The surface area of each is enlarged with 10-20 deep invaginations or tonsillar crypts in which th
Palatine tonsil
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are situated along the base of the tongue, are also covered by stratified squamous epithelium with crypts, and have many of the same features as palatine tonsils but lack distinct capsules.
Lingual tonsils
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is situated in the posterior wall of the nasopharynx, is covered by pseudostratified ciliated columnar epithelium, and has a thin underlying capsule.
pharyngeal tonsil
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▪ Location: Wall of the small intestine, resembling tonsils in structure
▪ Capture & destroy bacteria in the intestine
PEYER’S PATCHES
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▪ Location: Tubelike offshoot of the 1st part of the large intestine
▪ Has lymphoid follicles, that capture & destroy bacteria.
appendix
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2 types of immnunity
innate immunity and adpative immunity
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the ability to resist infection by means of normally present body functions.
INNATE IMMUNITY
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acquired gradually by exposure to microorganisms
adaptive immunity
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Non-specific and without memory
innate immunity
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Specific and with memory
Adaptive immunity
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innate immunity is mediated by:
Granulocytes and other leukocytes
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adaptive immunity is mediated by
lymphocytes and antigen presenting cells (APCs)
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cells involved in innate immunity
Phagocytes, Basophils, Macrophages, Dendritic cells
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cell involved in adaptive immunity
b and t cell
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response time of innate immunity
immediate
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response time of adaptive immunity
delayed
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occurrence of innate immunity
natural
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occurrence of adaptive immunity
stimulated
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processes involved in innate immunity
phagocytosis and antigen preservation
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processes involved in adaptive immunity
b-cell activation and t-cell activation
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specifity of innate immunity
non-specific
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specificity of adaptive immunity
specific
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life span of innate immunity
short term
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span of adaptive immunity
long term
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phatogen recognition of innate immunity
toll-like receptors
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phatogen recognition of adaptive immunity
memory cells
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Mechanisms protect against a variety of invaders. • Responds immediately to protect the body from all foreign materials.
INNATE IMMUNITY/INNATE BODY DEFENSE
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what are the first line of defense?
skin
intact mucous membranes
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Forms mechanical barrier to foreign materials
skin
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Skin secretions (pH 3-5) make epidermal surface acidic, inhibits bacterial growth; sebum also contains bacteria-killing chemicals.
acid mantle
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Provides resistance against acids, alkalis, & bacterial enzymes.
keratin
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Form mechanical barrier that prevents entry of pathogens
intact mucous membranes
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Traps microorganisms in respiratory & digestive tracts
mucus
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Filter & trap microorganisms in nasal passages
nasal hairs
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Propel debris-laden mucus away from lower respiratory passages
cilia
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Contains concentrated HCl & protein-digesting enzymes that destroy pathogens in stomach
gastric juice
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Inhibits growth of bacteria & fungi in female reproductive tract
acid mantle of vagina
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Continuously lubricate & cleanse eyes (tears) & oral cavity (saliva); contain lysozyme, an enzyme that destroys microorganisms
Lacrimal secretion (tears); saliva
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First Line of Defense
Surface Membrane Barriers
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Second Line of Defense
Cellular & Chemical Defenses
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what are the second line of defense?
phagocytes
natural killer cells
inflammatory response
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Engulfs foreign material into a vacuole & enzymes from lysosomes digest the material
phagocytes (neutrophil and macrophages)
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promote cell lysis (releasing perforins) by direct cell attack against virus-infected/cancerous body cells
natural killer cells
97
Triggered when body tissues are injured.
inflammatory response
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5 cardinal signs
rubor (redness)
calor (heat)
tumor (swelling)
dolor (pain)
functio laesa (loss of function)
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Results in a chain of events leading to protection and healing. • Prevents spread of injurious agents to adjacent tissues, disposes of pathogens & dead tissue cells, & promotes tissue repair.
• Releases chemical mediators that attract phagocytes (& immune cells) to the area
inflammatory response
100
LEUKOCYTES IN PERIPHERAL BLOOD
Neutrophils
Eosinophils
Basophil
Monocyte
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AKA POLYMORPHONUCLEAR NEUTROPHILIC (PMN) LEUKOCYTE, it represents approximately 50% to 75% of the total peripheral WBCs in adults.
neutrophils
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These are around 10 to 15 μm in diameter with a nucleus that has between two to five lobes. Hence, they are often called
segmented neutrophils
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2 types of neutrophil granules
azuropholic or primary granules
specific or secondary granules
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Azurophilic or primary granules contain antimicrobial products such as
myeloperoxidase
lysozyme
elastase
proteinase 3
cathepsin G
defensins
105
Specific granules, also known as secondary granules, contain
lysoxyme
lactoferrin
gelatinase
collagenase
respiratory burst components
106
Eosinophils are approximately 12 to 15 μm in diameter and normally make up between 1% and 3% of the circulating WBCs in a nonallergic person.
o Their number increases in an allergic reaction or in response to certain parasitic infections.
o The nucleus is usually bilobed or ellipsoidal and is often eccentrically located. o Eosinophils are capable of phagocytosis but are much less efficient than neutrophils because they are present in smaller numbers, and they lack digestive enzymes
Eosinophils
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can neutralize basophil and mast cell products. o They can use cationic proteins to damage cell membranes and kill larger parasites that cannot be phagocytized.
Eosinophils
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the regulation of the immune response, including the regulation of mast cell function.
important role of Eosinophils
109
The least numerous WBC found in peripheral blood, representing less than 1% of all circulating WBCs.
o The smallest of the granulocytes, basophils are slightly larger than RBCs (between 10 to 15 μm in diameter) and contain coarse, densely staining deepbluish-purple granules that often obscure the nucleus.
Basophils
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Constituents of these basophil granules includes
histamine, cytokines, growth factors, and a small amount of heparin
111
regulate some T helper (Th) cell responses and stimulate B cells to produce the antibody IgE
Basophils
112
are the largest cells in the peripheral blood with a diameter that can vary from 12 to 22 μm (the average is 18 μm). One distinguishing feature is an irregularly folded or horseshoe-shaped nucleus that occupies almost onehalf of the entire cell’s volume.
o Cytoplasm stains a dull grayish blue and has a ground-glass appearance because of the presence of fine dustlike granules.
monocyte
113
2 types of monocyte granules
first type and second type
114
They stay in peripheral blood for up to ________; they then migrate to the tissues and become known as macrophages.
30 hours
115
arise from monocytes, which can be thought of as macrophage precursors because additional differentiation and cell division take place in the tissues.
macrophages
116
play an important role in initiating and regulating both innate and adaptive immune responses
macrophages
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resemble basophils, but they come from a different lineage. Mast cells are distributed throughout the body in a wide variety of tissues.
o Mast cells are larger than basophils with a small round nucleus and more granules. Unlike basophils, they have a long-life span of between 9-18 months.
mast cell
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helps to distinguish them from basophils because they contain acid phosphatase, alkaline phosphatase, and protease, as well as histamine.
mast cells
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are so named because they are covered with long membranous extensions that make them resemble nerve cell dendrites.
dendritic cells
120
dentric cells were discovered by
Steinman and Cohn in 1973
121
o It is considered the most effective APC in the body, as well as the most potent phagocytic cell.
dendritic cell
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an enzyme made by neutrophils and cells of epithelial barriers, which hydrolyzes bacterial cell wall components, killing those cells.
lysozyme
123
short cationic polypeptides produced by neutrophils and various epithelial cells that kill bacteria by disrupting the cell walls.
defensins
124
Paracrine factors from leukocytes and virus-infected cells that signal NK cells to kill such cells and adjacent cells to resist viral infection. ▪ Mobilize the immune system.
interferon
125
Normally acid pH inhibits bacterial growth ▪ Urine cleanses the lower urinary tract as it flushes from the body
Fluids with acid pH
126
Abnormally high body temperature, a systemic response to invading microorganisms.
fever
127
Hypothalamus heat regulation can be reset by
pyrogens
128
Specific defense, required for each type of invader
3rd line of defense
129
recognizes & acts against particular foreign substances.
Antigen-specific
130
not restricted to the initial infection site
systemic
131
recognizes & mounts a stronger attack on previously encountered pathogens.
has memory
132
Types of Immunity
humoral immunity
cellular immunity
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• Antibody-mediated immunity
• Cells produce chemicals for defense.
humoral immunity
134
• Cell-mediated immunity (lymphocytes) • Cells target virus-infected cells.
cellular immunity
135
Any substance capable of exciting the immune system and provoking an immune response.
antigens
136
Common examples of antigen
• Foreign proteins • Nucleic acids •
Large carbohydrates
• Some lipids • Pollen grains • Microorganisms
137
• Our immune cells do not attack our own proteins. • Our cells in another person’s body can trigger an immune response because they are foreign restrict donors for transplants
self-antigens
138
small molecules are not antigenic, but when they link up with our own proteins, can elicit an immune response (harmful rather than protective because it attacks our own cells)
Hapten (incomplete antigen)
139
key cells involved in the adaptive immune response
lymphocytes
140
become immunocompetent in the bone marrow; produce antibodies & oversee humoral immunity. ▪ B cell precursor end result is a B lymphocyte programmed
b cells
141
Other surface proteins that appear on the B cell include
CD19, CD21, and class II major histocompatibility complex (MHC) molecules
142
become immunocompetent in the thymus; nonantibody-producing lymphocytes that constitute the cell-mediated arm of the adaptive defense system
t-cell
143
3 subtypes of t-cell
Helper T cells (Th cells)
Cytolytic cells
Regulatory T cells
144
Helper T cells (Th cells) are characterized by
CD4
145
Activated by such binding, helper T cells greatly assist immune responses by producing cytokines that promote
Helper T cells (Th cells)
146
Cytolytic cells: characterized by
CD8
147
Also called killer T cells, they attach to the cell sources of the antigens and remove them by releasing perforins and granzymes, which trigger apoptosis
Cytolytic cells
148
Regulatory T cells (Tregs or suppressor T cells): characterized by
CD4+ AND CD25+
149
play crucial roles in allowing immune tolerance, maintaining unresponsiveness to self-antigens and suppressing excessive immune responses. ▪ serve to inhibit specific immune responses
regulatory t cells
150
represent a smaller subpopulation whose TCRs contain γ (gamma) and δ (delta) chains instead of α and β c
γδ T lymphocytes
151
A small percentage of lymphocytes do not express the markers of either T cells or B cells. They are named natural killer cells because they have the ability to kill target cells without prior exposure to them
NK CELLS
152
NK CELLS FOUND MAINLY IN THE
liver, spleen, and peripheral blood
153
There are no surface markers that are unique to NK cells, but they express a specific combination of antigens that can be used for identification which are
CD16 and CD56
154
NK cells have a half-life
7-10 days
155
Engulf antigens & then present fragments of them, on their own surfaces where they can be recognized by T cells
Antigen-Presenting Cells (APCs)
156
3 major types of Antigen-Presenting Cells (APCs)
dendritic cells
macrophage
b lymphocytes
157
(Langerhans cells): present in connective tissues & in the epidermis, best situated to act as mobile sentinels
dendritic cells
158
arise from monocytes, widely distributed throughout the lymphoid organs & connective tissues, where they act as phagocytes
macrophages
159
TYPES OF IMMUNITY (ADAPTIVE)
humoral immunity
cellular immunity
160
▪ Antibody-mediated immunity
▪ Cells produce chemicals for defense.
humoral immunity
161
▪ Cell-mediated immunity (lymphocytes)
▪ Cells target virus-infected cells
cellular immunity
162
Cells target virus-infected cells.
CELLULAR IMMUNITY
163
B lymphocytes with specific receptors bind to a specific antigen
• The binding event activates the lymphocyte to undergo clonal selection
HUMORAL IMMUNITY
164
2 types of HUMORAL IMMUNITY
primary humoral response
secondary humoral response
165
a large number of clones are produced.
• Most B cells become plasma cells: produce antibodies to destroy antigens (lasts for 4-5 days)
primary humoral response
166
long-lived memory of some B cells
▪ A 2nd exposure causes a rapid response (stronger & longer-lasting)
• Can be active or passive
secondary humoral response
167
B cells encounter antigens & produce antibodies
ACTIVE IMMUNITY
168
▪ Immunological memory does not occur.
▪ Protection provided by “borrowed antibodies” ends when they naturally degrade in the body
PASSIVE IMMUNITY
169
• Antigens must be presented by macrophages (or by other APCs) to an immunocompetent T cell (antigen presentation)
• T cells must recognize nonself & self (double recognition)
• After antigen binding, clones form as with B cells, but different classes of cells are produced
CELLULAR (CELL-MEDIATED) IMMUNE RESPONSE
170
o Soluble proteins secreted by B cells (plasma cells)
o Carried in blood plasma.
o Capable of binding specifically to an antigen
ANTIBODIES/IMMUNOGLOBULINS
171
Structure:
▪ 4 amino a cid chains linked by disulfide bonds.
▪ 2 identical amino acid chains are linked to form a heavy chain.
▪ The other 2 identical chains are light chains.
▪ Specific antigen-binding sites are present.
ANTIBODIES/IMMUNOGLOBULINS
172
• Antibodies prepared for clinical testing/diagnostic services.
• Produced from descendants of a single cell line.
• Pure antibody preparations that exhibit specificity for one, & only one, antigen
MONOCLONAL ANTIBODIES
173
Examples of uses:
▪ Delivers cancer-fighting drugs to cancerous tissue (early cancer diagnosis)
▪ Diagnosis of pregnancy
▪ Treatment after exposure to hepatitis & rabies.
MONOCLONAL ANTIBODIES
174
5 CLASSES OF ANTIBODIES (GAMDE/GAMED)
IgG
IgA
IgM
IgD
IgE
175
• most abundant with 75 – 85%
• Highly soluble
• Functions: activates phagocytosis & neutralizes antigens
IgG
176
4 TYPES OF IGG
IgG1
IgG2
IgG3
IgG4
177
can across the placenta
IgG1
178
cannot across the placenta
IgG2
179
can fix the complement.
IgG3
180
cannot fix the complement.
IgG4
181
against certain infections until the newborn’s own adaptive immune system is acquired.
IgG Primary immunity
182
• Anamnestic Response Antibody
• Most abundant in SERUM.
• Most efficient in Precipitation.
• Activates Complement Classical Pathway, Opsonin Viral Neutralization, Antibody-dependent Cellular Cytotoxicity
IgG
183
• Present in almost all exocrine secretions with 10-15%
• Dimeric: heavy chains of 2 monomers are united by a polypeptide called “J chain”
• Produced by plasma cells in digestive, respiratory and reproductive tracts.
• Secretory component: released by epithelial cells as IgA undergoes
transcytosis.
• Function: protects mucosae
IgA
184
found in blood.
Monomeric IgA
185
found in secretions (saliva, tears, breastmilk); the only antibody with secretory components.
Dimeric IgA
186
B-cell production of IgA primarily happens in____
MALT
187
5-10% in population
IgM
188
present in plasma
Pentameric IgM
189
present on the surface of naïve B cell.
Monomeric IgM
190
• With J-chain (JOINING CHAIN)
• B-lymphocyte surface (monomer)
• Exits in a pentameric form united by a J chain.
• Initial response to an antigen.
• most effective antibody class in activating the complement system
• PRIMARY RESPONSE ANTIBODY
• Activates Complement Classical Pathway
• Indicates Acute Infection
IgM
191
• Found on the surface of naïve B cells.
• With extended hinge region.
• Role in B-Cell: Acts as antigen receptor for ACTIVATION, MATURATION, AND DIFFERENTIATION.
• Least abundant with 0.001%
• Least understood class of antibody
IgD
192
• Formerly Reagenic Antibody aka Homocytotropic Antibody
• Most Heat Labile
• Binds to Mast Cells, Eosinophils, and Basophils.
• Less abundant with 0.002%
• bound to receptors on the surface of mast cells and basophils
• When encounters the antigen, the antigen-antibody complex triggers
substances such as histamine, heparin, and leukotrienes.
• Functions: destroys parasitic worms and participates in allergies.’
IgE
193
Binding of antigen-binding site of an antibody with antigen causes
ACTIONS OF ANTIBODY
194
3 types of ACTIONS OF ANTIBODY
NEUTRALIZATION
AGGLUTINATION
PRECIPITATION
195
antibody covers the biologically active portion of microbe toxin
NEUTRALIZATION
196
antibody cross-links cells (ex. Bacteria) forming a “clump”.
AGGLUTINATION
197
Antibody cross-links circulating particles (ex. Toxins), forming an insoluble antigen- antibody complex.
NEUTRALIZATION
198
Exposed Fc portion following antigen binding by antibody promotes:
COMPLEMENT FIXATION
OPSONIZATION
ACTIVATION OF NK CELLS
199
Fc region of antibody binds complement proteins; complement is activated.
COMPLEMENT FIXATION
200
Fc region of antibody binds to receptors of phagocytic cell, triggering phagocytosis.
OPSONIZATION
201
Fc region of the antibody binds to an NK cell, triggering release of cytotoxic chemicals.
ACTIVATION OF NK CELLS
202
2 TYPE OF ANTIGEN PRESENTATION
Major Histocompatibility Complex (MHC)
Human Leukocyte Antigens (HLAs)
203
- Abundant antigen-presenting proteins.
- Made in rough ER and golgi apparatus.
Major Histocompatibility Complex (MHC)
204
2 TYPES OF Human Leukocyte Antigens (HLAs)
MHC Class I
MHC Class II
205
present antigens to cytotoxic cells with CD8+ receptors.
MHC Class I
206
present antigens to helper T cells with CD4+ receptors.
MHC Class II
207
Encoded by genes in large chromosomal loci having high degrees of allelic variation between different individuals.
Human Leukocyte Antigens (HLAs)
208
Failure of the third (and fourth) pharyngeal pouches to develop normally in the embryo leads
to ________, characterized by thymic hypoplasia (or aplasia). Lacking many or all thymic epithelial cells, such individuals cannot produce T lymphocytes properly and have
severely depressed cell-mediated immunity.
o The retrovirus that produces acquired immuno
DiGeorge syndrome
209
Inflammation of the tonsils, ______, is more common in children than adults. Chronic inflammation of the pharyngeal lymphoid tissue and tonsils of children often produces hyperplasia and enlargement of the tonsils to form “adenoids,” which can obstruct the eustachian tube and lead to middle ear infections.
tonsillitis
210
Neoplastic proliferation of lymphocytes, producing a _______ may occur diffusely but is often located in one or more lymph nodes.
malignant lymphoma
211
Such growth can completely
obliterate the normal architecture of the node and convert it to an enlarged, encapsulated structure filled with lymphocytes; a condition called ______.
lymphadenopathy
212
the immune system does not distinguish between self & nonself and body produces antibodies (auto-antibodies) & sensitized T cells that attack & damage its own
tissues
Autoimmune Diseases
213
Failure of the immune system to recognize & tolerate the body's own cells & tissues as "self“.
- Key factor in the development of autoimmune diseases
- Appearance of self-proteins in the circulation that have not been exposed to the immune system (sperm, eggs, eye lens)
- Cross-reaction of antibodies produced against foreign antigens with self-antigens:
Self-Tolerance Breakdown
214
(caused by Streptecoccus pyogenes bacteria): trigger an immune response in which antibodies produced to destroy the bacteria instead attack & inflame the connective tissues in joints, heart valves, & other organs
Rheumatic heart fever
215
Rheumatoid arthritis: joints
Anti-Rheumatoid Factor
216
Myasthenia gravis: Ach receptors at the neuromuscular junction
Anti-acetylcholine receptor
217
Multiple sclerosis: white matter (myelin sheaths)
Anti-myelin sheath
218
Graves’ disease: thyroid gland
Anti-TSH receptor
219
Type 1 diabetes mellitus: pancreatic beta cells
Anti-islet cells
220
Systemic lupus erythematosus (SLE): kidneys, heart, lungs, & skin
Anti-Nuclear Antibodies
221
Glomerulonephritis: severe impairment of kidney function
Antineutrophilic Cytoplasmic Antibody (ANCA)
222
o A person who is overly reactive to a substance that is tolerated by most other people is said to be allergic/hypersensitive
o Allergens: antigens that induce an all
ALLERGIES (HYPERSENSITIVITIES)
223
antigens that induce an allergic reaction
Allergens
224
2 TYPE OF ALLEGIES
Immediate (acute) hypersensitivity (Type 1)
Delayed hypersensitivity (Type 4)
225
▪ Triggered by release of histamine from IgE binding to mast cells
▪ Reactions begin within seconds of contact with allergen
Immediate (acute) hypersensitivity (Type 1)
226
dangerous, systemic response; allergen directly enters the blood & circulates rapidly through the body
Anaphylactic shock
227
▪ Triggered by the release of cytokines from activated helper T cells
▪ Symptoms usually appear 1–3 days after contact with antigen.
Delayed hypersensitivity (Type 4)
228
skin contact with poison ivy, some heavy metals (lead, mercury, & others), & certain cosmetic & deodorant chemicals
Allergic contact dermatitis
229
Rare inherited disorder in which both B cells and T cells are missing/inactive
▪ May be congenital/acquired.
▪ Severe combined immunodeficiency disease (SCID)
IMMUNODEFICIENCIES
230
▪ Marked deficit of both B & T cells.
▪ Afflicted children have essentially no protection against pathogens of
any type.
▪ AKA bubble boy disease, named for David Vetter, who was born with
the condition & lived behind plastic barriers to protect him from
microbes.
Severe combined immunodeficiency disease (SCID)
231
▪ Caused by a retrovirus (HIV) specifically targets & destroys helper T cells.
▪ The retrovirus that produces acquired immunodeficiency syndrome (AIDS) infects and rapidly kills helper T cells. Reduction of this key lymphocyte group cripples the patient’s immune system rendering
them susceptible to opportunistic bacterial, fungal, protozoan, and
other infections that usually dealt with easily in immunocompetent
individuals.
Acquired immune deficiency syndrome (AIDS)
232
4 MAJOR TYPES OF GRAFTS
Autografts
Isografts
Allografts
Xenografts
233
tissue transplanted from 1 site to another on the same person
(ideal)
Autografts
234
tissue grafts from an identical person (identical twin) (ideal)
Isografts
235
tissue taken from an unrelated person
▪ More successful with a closer tissue match
▪ Most used, taken from a recently deceased person
Allografts
236
tissue taken from a different animal species (never successful)
Xenografts
237
o Medical treatment aimed at suppressing/weakening the body's
immune system, given to patient after surgery to prevent rejection.
o Includes: corticosteroids to suppress inflammation, antiproliferative drugs, radiation (X-ray) therapy, & immunosuppressor drugs
o Major problem: cannot protect the body against other foreign agents
IMMUNOSUPPRESSIVE THERAPY
