Flashcards in Lecture 1 Deck (123):
defense mechanisms which provide protection from infectious disease
What 2 things comprise the immune system?
cells and molecules which collectively mediate an immune response
Microbes can cause...
an immune response, with tissue injury (immunopathology)... collateral damage
What is an autoimmune response?
A pathological condition in which an immune response occurs against oneself
What are defined as substances which induce an immune response?
What three things do an antigen include?
proteins, carbohydrates, lipids, and nucleic acids
Microbes have many different _____ which can be recognized by the immune system.
What determines what an antigen responds to?
antigenic determinants, there can be multiple for one antigen
What is the smallest antigenic determinant to which an antibody can be made of?
three to six amino acids or five to six sugar residues
All large molecules are multideterminant...
have multiple epitopes
What do antibodies bind to?
Conformational antigenic deteminants which are dependent on folding of the molecule.
What do T cell receptors recognize?
linear amino acid sequences
What are Ags that can stimulate an immune response called?
All immunogens are antigens but,
not all antigens are immunogens
What cannot create an immune response but can bind to Ab's or TCR's?
What is the first line of defense against infection?
innate immune system
How does the innate immune system work?
It gives rise to the acute inflammatory response. and has some specificity for microbes, but no memory
What immune system takes longer to develop?
Adaptive immune system. It is very highly specific. and remembers that it has encountered a microbe previously.
Innate immunity exists...
before infections and is poised to respond rapidly to infections.
What does innate immunity respond to?
microbes and injured cells
Does innate immunity change the way it reacts when it is exposed to the same thing over and over again?
What kind of antigens does innate immunity recognize?
Common antigens belonging to groups of related microbes
Does innate immunity distinguish btw fine differences in microbes?
What are the three main principal components of innate immunity?
1. physical and chemical barriers
2. phagocytic cells(neutrophils, macrophages), dendritic cells, and natural killer (NK) cells and other innate lymphoid cells
3. blood proteins, including the complement system and other mediators of inflammation
Give 3 examples of cellular and chemical barriers in innate immunity.
skin, mucosal epithelia, antimicrobial molecules
Give 3 examples of blood proteins in innate immunity,
complement, acute phase proteins, cytokines, others
What type of cells respond to an innate response in innate immunity?
Phagocytes- mcarophages, neutrophils
natural killer cells
innate lymphoid cells
What cellular and chemical barriers are involved in adaptive immunity?
lymphocytes in epithelia; antibodies secreted at epithelial surfaces
What blood proteins are involved in adaptive immunity?"
antibodies and cytokines
What Cells are involved in adaptive immunity?
B and T Lymphocytes
How much diversity does innate immunity have?
limited, germline encoded
HOw much diversity does adaptive immunity have?
very large; receptors are produced by somatic recombination of gene segments
What specificity does adaptive immunity have?
microbial and nonmicrobial antigens
What specificity does innate immunity have?
for molecules shared by groups of related microbes and molecules produced by damaged host cells.
The innate immune system is a
decision making stage of an immune response in addition to inflammation.
The systems work together...
cells from innate immunity are used in adaptive immune system
How do cells communicate?
Direct cell-to-cell contact.
What does cell communication involve?
cytpkines and chemokines
What are large group of small secreted proteins w diverse stuructes and functions?
What do cytokines do?
They regulate and coordinate many activites of the cells of innate and adaptive immunity.
Each cell express a set of
specifice signaling receptors for several cytokines.
What are the functions of cytokines.
Growth and differentiation of all immune cells, activation of effector functions of lymphocytes and phagocytes
What is a large subset of structurally related cytokines?
Chemokines, they regulate cell migration and movement.
What are the two types of lymphocytes?
B cells and T cells
What is critical to the development of specific immunity?
interactions btw T and B cells, and interaction btw Tcells and antigen-presenting cells (APCs)
Where do T cells mature?
Why do t cells mature?
stmulation by Ag, give rise to cellular immunity
Where doe B cells mature?
What do B cells give rise too?
Immunity that involves production of soluble molecules- immunoglobulins
ensures that the immune response to a mecrobe (or nonmicrobial antigen) is targeted to that microbe (or antigen)
enables the immune system to respond to a lg variety of antigens
increases the ability to combat repeat infections by the same microbe
increases the number of antigen-specific lymphocytes to keep pace w microbes
generates responses that are optimal for defense against different types of microbes
allows the immune system to recover from one response so that it can effectively repsonse to enwly encountered antigens
contraction and homeostasis
Who postulated that immune cells use receptors, which he called side chains, to recognize microbial toxins and secrete these receptors to combat microbes?
Paul Ehrlich: Father of Humoral Immunity
What term did Paul Ehrlich coin?
Antibodies for the serum proteins that bound to toxins.
What are Paul Ehrlich's concepts model?
function of B cells
What produce antiboies in the blood and mucosal secretions?
B lymphocytes that mediate the humoral adaptive immunity.
What to abs recognize?
microbial antigens. And then abs nuetralize the infectivity of the microbes and targe microbes for elimination by various effector mechanisms
What is the principal defense mechanism agains extracellular microbes and thier toxins?
Hummoral adaptive immunity Abs which can bind to these microbes and toxins and assist in their elimination
Who is the found of cellular theory of immunity?
Elie Metchnikoff, he stated that host cells are the principal mediators of immunity; however, he was unable to prove that specific immunit to microbes could be mediated by cells. he shared the nobel prize with Ehrlich's in 1908.
In 1883 Eli Metchnikoff disovered????/
special immune cells and named them phagocytes
The cellular theory of immunity became firly re established in the 1950's when it was shown the resistance to an intra cellular bacterium could be transferred....
with cells but not w serum
What causes the specificity of cell mediated immunity?
T lymphocytes, which often function in concert w phagocytes to eliminate microbes
What immunity do B lymphocytes secret antibodies that prevent infections and eliminate extracellular microbes?
What is cell mediated immunity mediated by?
T lymphocytes and is also called cellular immunity.
What does cellular immunity mediate?
Defense against intracellular microbes, such as viruses and some bacteria, where they are inaccessible to circulating antibodies
What is the function of cell mediated immunity?
Destruction of microbes residing in phagocytes or the killiing of infected cells to eliminate reservoirs of infection
What cells contribute to eradication of extracellular microbes?
T helper lymphocytees by helping B cells maek effective antibodies.
When do T helper lymphocytes activate macrophages to kill phagocytized microbes? Or cytotoixic T lymphocytes directly destroy infected cells?
cell mediated immunity or cellular immunity
What do clones of cells specific for Ag do
neutralize or eliminate Ag, clonal slection
Who suggested the clonal selection hypothesis?
Dr. Jerne in 1955 and further developed by Dr. Burnet in 1957
What does the clonal selection hypothesis explain/
how the immune system could respons to a lg number of variety of ags
When do Ag specific clones develop according to the clonal hypothesiss?
Before and independent of exposure to Ag
What does a clone refer to?
A lymphocyte of one specificity and its progeny
conferred by a host response to a microbe or microbial Ags
conferred by adoptive transfer of antibodies or T lymphocytes specific for the microbe
What suppress and prevent immune response from self antigets?
Regulatory T cells
What 2 types of cells are phagoyctes
neutrophils and macrophages
Steps in functinoal response by phagocytes
What are lysosomes that contain enzymes and other microbicidal substances?
Dendritic cell diffintiate into
classical DC's and plasmacytoid Dcs (pDCs)
What is the goal of vaccination?
generation of memory response
Memory cells response faster and more effectively than?
naive T cells
Who was the first doctor to make a vacination?
Dr Edward Jenner agains smallpox with a 8 year old boy
Who is considered the father of immunology?
What provides immunologic memory?
What recognize Ags on infected cells and kill these cells?
cytotoxic T lymphocytes
What is the primary function of phagocytes?
to ingest and destroy microbes and get rid of damaged tissues(scavenger function)
What are called polymorphonuclear leukocytes?
neutrophils, bc their nucleus is segmented into three to five connected lobules
What is the most abundany leukocyte?
What mediate the earliest phases of inflammatroy reactions?
What do neutrophils arise from and what is their precursor?
the bone marrow, mononuclear phagocytes
What stimulated the production of neutrophils?
the cytokine called granulocyte colony stimulating factor (G-CSF)
What happens when neutrophils encounter hyphae?
They are not able ot internalize them. azurophilic granules are free to deliver their contents instead into the nucleus, which triggers chromatin decondensation and the release of NETs
What do NETs do?
Contribute to the immobilizaiton and killing of extracellular organisms, but at the cost of some tissue damage
What is NET formation mediated by?
Cell death-dependent process referred to as NETosis, it is very active process
What are NETs composed of?
DNA and histones and are decorated by proteins from primary granules and secondary granules
What can be another source of DNA for NET formation?
What plays role in innate and adaptive immune repsonse?
mast cells, basophils, and eosinophils
What does mast cells basophils and eosinophils protect agains?
helminthese and reactions that cuase allergic diseases
What does mast cells basophils and eosinophils share the common featuer of?
cytoplamic granules filled w vaious inflammatory and antimicrobial mediators
Mast cells are stained?
purple with Giemsa
Blood basophils are stained
blue with giemas
eosinophils are stained
red with acidic dye eosin
What are common at sites in the body that are expose to the external envirtonment?
Where are mast cells found?
in close proximity to blood vessels, where they can regulate vascular permeability and effector-cell recruitment
Mast cells do not have direct cell to cell communication, how do they communicate?
effector cells through the release of mediators
What does the mononuclear phagocyte system consist of?
monocytes and resident tissue macrophages
What do macrophages play a role in?>
innate and adaptive immunity
Someimtes, tissues are poprulated with long lived resident macrophages which assume what role?
specialized phenotypes depending on the organ
Where do monocytes arise from?
bone marrow, driven by monocyte/macrophage colony stimulating factor(M-CSF)
What enter the blood ciruculation and then migrate into tissues where they furthe rmature into macrophages, especially during inflammation?
Where is the orgin and maturation of mononuclear phagocytes for fetus?
HSF... GM-CFU.... M-CFU...monoblast...pro-monocyte... inflammatory monoctye or resident monocyte to become specific
What is opsonization?
the immune serum enhance the phagocytosis of bacteria by coating the bacteria