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Immunology > Lecture 1-cells, Organs > Flashcards

Lecture 1-cells, Organs Flashcards

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1
Q

What is immunity?

A

Recognition of and reaction to foreign agents

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2
Q

What are foreign agents?

A

Pathogens
Host cells that infected, necrotic, neoplastic
Allergens, chemicals
Mismatched tissue or blood.
Foreign agents are composed of antigens which can be: proteins, carbohydrates (strong antigens-make good vaccines), nuclei acids ne lipids (weak antigens)

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3
Q

What are the mechanisms used by leukocytes to destroy antigens?

A

Phagocytosis-Ingestion and digestion of antigen particles
Cytotoxicity- induction of apoptosis in tumors, tissue grafts and infected host cells
Synthesis of soluble factors- antibodies, complement, cytokines, aid in the elimination of antigens

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4
Q

What are the branches of immunity?

A

Innate Vs adaptative

Humoral VS cell mediated

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5
Q

What are the characteristics of innate immunity?

A 
Natural, native
Present and functional at birth
Rapid response (within minutes)
Discriminate between self and non self
Low specificity
No memory
Not enhanced by vaccination
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6
Q

What are the components of innate immunity?

A

Natural barriers (skin, mucus, ph extremes, sneezing)
Phagocytes, granulocytes, natural killer cells
Soluble mediators(complement, CRP, cytokines)
Pattern recognition receptors
Normal flora microbes

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7
Q

What are the characteristics of adaptive immunity?

A 
Acquired
Induced by antigen contact 
Slow response (take days)
Able to discriminate between self and non self
Highly specific
Memory
Enhanced by vaccination
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8
Q

What are the components of the adaptive immunity?

A

B lymphocytes, plasma cells
Antibodies/immunoglobulins
T lymphocytes

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9
Q

What is the mechanism of clinal selection?

A

Antigen is specific to one type of T or B cells
Contact of antigen with matched receptor cells causes proliferation of that cell
From one cell we have thousand of cells for that antigen
proliferation is followed by differentiation
Differentiation gives rise to cells secreting specific antibody for the antigen and memory cells
Memory cells reside in spleen and lymph nodes and can be used for further production of antibodies

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10
Q

What are the characteristics of humoral immunity?

A

Most effective against extracellular bacteria
Antibody (immunoglobulin) is the most common
But includes:
Complement-pathogen lysis
C-reactive protein (CRP)-activates complement, general marker of infection and inflammation

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11
Q

What are the characteristics of the cell mediated immunity (CMI)?

A

Effective against intracellular and extracellular pathogens, tumors, damaged host cells
Can be :
Phagocytes-monocytes, neutrophils, eosinophils, macrophages
Granulocytes- neutrophils, eosinophils, mast cells, basophils
Cytotoxic cells-NK cells, Tc cells–> apoptosis of targets

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12
Q

What is opsonization?

A

Humoral immunity and CMI work together
Opsonins are ( antibody, complement and CRP) are substances that coat the capsule of bacteria to facilitate phagocytosis
Opsonins neutralize anti phagocytic property of bacterial capsules

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13
Q

What is hematopoiesis?

A

Formation of red blood cells, leukocytes and platelets from multipotent stem cells
Formation of 2 major lineages
Myeloid
Lymphoid

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14
Q

What is the mechanism of formation of the lymphoid lineage cells?

A

Stem cell under the influence of IL-7 gives the common lymphoid progenitor (CLP)
CLP gives B lymphocytes, natural killer cells and in the thymus T lymphocytes
T lymphocytes can further differentiate into T helper cells and cytotoxic T cells

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15
Q

What is the mechanism of the formation of the myeloid lineage cells?

A

Stem cell differentiates into common myeloid progenitor (CMP)
CMP+erythropoietin gives erythropoietin CFU which differentiates into erythrocytes
CMP+IL-3, GM-CSF+ thrombopoietin(IL-11) gives megakaryocyte which gives platelets
CMP+IL-3, GM-CSF gives basophil CFU which differentiates into basophils
CMP+IL-3, GM-CSF+Il-5 gives eosinophil CFU which differentiates into eosinophils
CMP+IL-3+GM-CSF gives granulocyte-monocyte CFU
G-M/CFU+G-CSF (filgrastim) gives neutrophils
G-M/CFU +M-CSF gives monocytes

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16
Q

What a re some clinical uses of CSF and ILs?

A

Erythropoietin (Epoetin, EPO)- Reverse anemia, restore RBCs especially in renal failure
G-CSF (Filgrastim)- Recovery of bone marrow, restore PMNs
GM-CSF (Sargramostim)-Recovery of bone marrow, restore PMNs, monocytes and macrophages
Interleukin 11 (oprelvekin)-Reverce thrombocytopenia, restore platelets
Thrombopoietin (TPO)- Reverse thrombocytopenia, restore platelets

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17
Q

What are the markers and cell function of B lymphocytes?

A

CD markers: CD19, CD 20, CD21

Function: antibody secretion-humoral immunity

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18
Q

What is the marker common to all T lymphocytes?

A

CD 3

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19
Q

What are the markers and function of T helper cells?

A

CD3, CD4

Function: cytokines secretion

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20
Q

What are the markers and function of the T regulatory cells (Treg)?

A

CD3, CD4, CD 25

Function: prevent autoimmunity

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21
Q

What are the markers and function of cytotoxic T cells (Tc)?

A

CD3, CD8

Functions: Killing of infected or neoplastic cells, rejection of grafts

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22
Q

What a re the markers and functions of natural killer cells (NK)?

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A

CD16, CD56

Functions: killing of infected or neoplastic cells, rejection of grafts

23
Q

What are the markers and functions of Natural Killer T cells (NKT)?

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A

CD3, CD16, CD56 plus TCR and NK1.1

Function: prevent infection through gut

24
Q

What are the functions of the innate lymphoid cells (ILCs)?

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A

Protection and inflammation of mucosa

25
What are the characteristic of B lymphocytes?
Develop in bone marrow (humans), bursa (birds) In infant they are produced in the bone marrow and liver Function in humoral immunity Produce antibodies (immunoglobulins/Ig)-toxin and microbe neutralization, opsonization and complement activation Differentiate into plasma cells or memory B cells
26
What are the characteristics of T lymphocytes?
Mature in thymus All express TCR (specificity) and CD3 (signal transduction) Differentiate into T helper cells, cytotoxic T cells and T regulatory
27
What are the subdivisions of the T helper cellls?
TH1- promote cell mediated immunity TH2-promote antibody synthesis by B cells (allergies) TH17- promote clearance of extracellular bacteria and fungi, contribute to asthma and autoimmunity
28
What are the characteristics of the Natural Killer cells?
Only cells off the lymphoid lineage that are from the innate immunity Kill infected and neoplastic host cells Collaborates with IgG during antibody dependent cel mediated cytotoxicity (ADCC)
29
What are the characteristics of the mononuclear phagocytes?
Horseshoe-shaped nucleus Circulating monocytes Dendritic cells Tissue fixed macrophages-line for years and comprise the reticuloendothelial system (RES) RES is a filtering system for antigen removal from blood and lymph Function in phagocytosis, antigen processing and presentation
30
What are the types of mononuclear phagocytes?
``` Kupffer cells in the liver Alveolar macrophages in the lung Splenic macrophages Peritoneal macrophages Microglial cells in the brain Osteoclasts in the bone Mesangial cells in the kidneys Synovial A cells in the joints ```
31
What are the steps of phagocytosis?
Chemotaxis(migration) of macrophage toward bacterial f-met-leu-phe Adherence to microbe aided by opsonins Extension of pseudopodium to form phagosome Fusion of phagosome and lysosomes to form phagolysosome Digestion-lysozyme( also found in tears, saliva, sweat genitourinary secretions) breaks down peptidoglycan in bacterial cell wall Respiratory burst-ROS damage protein, DNA
32
What are the steps of antigen processing and presentation?
Processing-destruction of antigen in phagolysosome Presentation antigen fragments paired up with MHC Complex transported to macrophage surface and presented to T cell T cell can't see antigen unless presented along with MHC by APC
33
What are the characteristics of the dendritic cells?
``` Related to macrophages Found under epithelia,in most organs Langerhans cells in skin Most efficient APC Activate naive T cells ```
34
What are the characteristics of the polymorphomuclear granulocytes ?
Short-lived Bilobes or multilobed nucleus Granules contain enzymes (lysozyme, others) and lactoferrin harmful to microbes Produce ROS
35
What are the components of the polymorphonuclear granulocytes?
Neutrophils- killed extracellular bacteria-Phagocytosis and inflammation (60-%)-receptors for IgG Eosinophils-killed worms (helminths)- participate in immediate hypersensitivity reactions -Receptors for IgE Basophils-Killed worms-Participate in immediate hypersensitivity reactions , good source of histamine- receptors for IgE Mast cells-killed worms-participate in immediate hypersensitivity reactions, major source of histamine-receptors for IgE, tissue fixed, long lived
36
What are the characteristics of megakaryocytic lineage?
``` Megakaryocyte: Large cell with lobulated nucleus Gives rise to platelets/thrombocytes Platelet: Anucleate Blood cl;outing and inflammation ```
37
What is the normal count of WBC?
Total WBC should be between 4800-10,800 per microliters
38
What are the characteristics of lymphoid organs and tissues?
Sites of lymphocyte maturation, differentiation, proliferation Can be 2 types Primary Secondary
39
What are the general characteristics of primary lymphoid organs?
Antigen receptors are first expressed here consist of : Bone marrow-where B cells begin surface immunoglobin expression Thymus where T cell begins TCR expression
40
What are the general characteristics of secondary lymphoid organs?
B and T cells respond to antigens here (clonal selection) consist of: Lymph nodes Spleen-site of most antibodies production MALT-adenoids, tonsils, Peyer's patches, appendix, BALT
41
What are the characteristics of bone marrow?
Site of hematopoiesis Stem cells express CD34 and Stem Cells antigen 1 (SCA-1) used to harvest stem cells for immmune reconstitution Stromae cells secrete cytokines that drive differentiation Site of B cell maturation
42
What are the steps in B cells maturation?
``` Stem cell gives Pro B Pro B gives Pre B Pre B gives immature B Immature B gives Mature B Mature B differentiate into memory B cell or plasma cell ```
43
What are the characteristics of Thymus?
Site of T cell maturation Develops from 3rd and 4th pharyngeal pouches Reaches max size at puberty Atrophies with age
44
What is DiGeorge syndrome?
Defect associated with thymus Little/no thymus Few/no T cells-->heightened susceptibility to viruses and cancer 22q11.2 microdeletion Deficient parathyroids-->hypocalcemic tetany Deformed ears, facial anomalies Heart and kidney defects
45
What are the steps in T cell development in the thymus?
``` In the subscapsular region: Double negative thymocytes Neither CD4 or CD8 present In the cortex: Double positive thymocytes Both CD4 and CD8 present In the medulla: Single positive T cells-Either CD4 or CD8 present, both TCR and CD3 present Hassall's corpuscles-Function in dendritic cell and /or Treg maturation ```
46
What are the characteristics of lymph nodes?
Respond to antigens entering through skin or subcutaneous tissues Encapsulated clusters Function : in survey of lymph by macrophages storage/activation of B and T lymphocytes Antibody production Constant circulation of lymphocytes between lymph nodes, tissues, lymph and blood
47
What is the structure of the lymph node?
Cortex (B cells) Paracortex (T cells) Medulla
48
What is the characteristic of the cortex?
Primary follicles- naive B cells Secondary follicles-germinal centers contain dividing B cells No/few secondary follicles in patients with B cell deficiencies
49
What are the characteristics of paracortex?
Poorly developed in DiGeorge syndrome HEVs facilitate entry of lymphocytes from blood into node Enlarged during cellular immune responses
50
What are the characteristics of Medulla?
Cords contain lymphocytes and plasma cells | Sinuses contain macrophages, drain into efferent lymphatics
51
What are the characteristics of the spleen?
``` Responds to blood-borne antigens Major site of antibody synthesis Asplenic persons are susceptible to encapsulated bacteria like (strep pneumonia, H.influenza, Neisseria meningitis) Red pulp-hemocathereis White pulp- Lymphocytes ```
52
What are the characteristics of splenic white pulp?
PALS-T cells surround a central arteriole | B cells rich follicles-primary and secondary germinal centers
53
What are the characteristics of MALT?
``` Respond to antigens entering through mucosal surfaces B cells produce secretory IgA 50% of bodys lymphoid tissue GALT(Gut) BALT(Bronchus) GU-ALT(Genito-urinary) Peyers patches of small intestine Tonsils, adenoids, appendix, mesenteric lymph nodes etc. ```
54
What are the M cells?
Unique to Peyers patches | Epithelial cells that mediate transcyotosis of antigens from lumen to subepithelial T cells

Immunology (8 decks)

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