Adaptive Immunity Flashcards
MHC class II molecules are only present on which type of cells?
APCs
Which MHC class presents antigens from outside the cell? which one presents intracellular?
MHC I presents intracellular (CD8)
MHC II presents from outside (CD4)
goals of lymphopoiesis
generate a diverse set of B and T lymphocytes
eliminate lymphocytes with self-reactive receptors
where do B cells mature?
Bone marrow and spleen
(begins in bone marrow)
Does a macrophage need a helper T cell to get activated and then destroy what it has swallowed?
I believe so (adaptive slide 9)
What are the two divisions of the adaptive immune system?
humoral (antibodies) and cell-mediated (T and B)
Positive vs negative selection in T cells:
Positive selection: refers to maturing only functional cells that can respond to the presentation of antigen on MHC
negative selection: refers to causing apoptosis in cells that are self-reactive (self meaning host proteins)
What is the T cell referred to as once it matures but before it meet san antigen?
Naive
upon exposure, T cells undergo clonal selection so only those with highest affinity for given antigen proliferate
(T cells are born with CD4 and CD8 but eventually only one will stay)
3 T cell types:
helper, cytotoxic, suppressor
what are the chemicals called that get secreted by CD4 cells?
Lymphokines (recruit other immune cells and increase their activity)
ex. interleukins (main group of cytokines)
(cytokines main groups: interleukins and interferons)
Which types of infections are helper T cells most effective against?
Bacterial, fungal, parasitic because helper T cells respond to antigens on MHC II complexes which are for extracellular pathogens (viruses are intra)
Which types of infections are helper T cells most effective against?
Bacterial, fungal, parasitic because helper T cells respond to antigens on MHC II complexes which are for extracellular pathogens (viruses are intra)
What do suppressor T cells do?
help to tone down immune response once infection has been adequately contained
also turn off self-reactive lymphocytes to prevent autoimmune diseases (called self-tolerance)
What happens when immunoglobulins (antibodies) are secreted into body fluids rather than present on a cell surface?
- Once bound to a specific antigen, they may attract other leukocytes to phagocytize those antigens immediately (OPSONIZATION aka more susceptible to phagocytosis)
- May cause pathogens to clump together or agglutinate, forming large insoluble complexes that can be phagocytized
- Can block the ability of a pathogen to invade tissues (neutralizing the pathogen)
- Lysis of pathogen by complement activation
- Precipitation into tissues
response when antibody is on cell surface?
binding–> activation–> proliferation and formation of plasma + memory cells
(binding of an antigen to surface of mast cell causes degranulation, allowing the release of histamine and causing an inflammatory allergic reaction)
Clonal selection with B cells:
B cells that can bind the invading antigen with high affinity survive and proliferate, generating specificity
Constant region of antibodies:
The base of the Y is a region that cells such as NK cells, macrophages, monocytes, and eosinophils have receptors for, and that can initiate the complement cascade
Antibody molecules are like a fork in a meatball so antibodies don’t escape
(note: each b cell makes only one type of antibody but we have so many b cells that our immune system can recognize many antigens)
Types of antibodies:
IgG: “really important for bacterial infections”
-65-75%
-made by plasma cells
-predominant antibody made after rechallenge of antigen aka secondary response
-bind macrophage and neutrophil receptors and activate compliment
-deficiency can lead to bacterial infections
-have you had this before in the past?
IgM: First to appear in primary immune response
-initial antibody type made by neonates
-Major antigen receptor on surface of mature B cells
-important component of immune complexes in autoimmune diseases
-pentamer
-are you sick now?
IgD: found in minute amounts
-together with IgM is major receptor for antigen on naive B cell surface
IgE: present in very low concentrations
-arms mast cells and basophils via Fc region
-results in release of mediators of immediate hypersensitivity (allergic) response
IgA:7-15%
-predominant class in secretions (tears, saliva, nasal, sweat, GI, human milk)
-dimer (4 sites)
-fixes complement via alternate pathway and has potent antiviral activity
Which two antibody classes are very specific to killing and therefore are the only ones activating the complement cascade?
IgG, IgM
summary of antibody classes image on desktop
What do naive cells do with their free time?
Wait in lymph nodes for their specific antigen to come along
Primary response of B cells:
exposure–> proliferate (into plasma and memory B)
B cells wait in lymph nodes (can live forever, plasma cells die)
initial activation (primary response) takes 7-10 days
Memory B cells:
just produce IgG
live up to 10 years in lymph node (not forever????)
differentiate into IgG secreting plasma cells when reactivated
response limited to peptide antigens, not lipid or carb
What do cytokines do? What cells produce them?
Activate cells of innate and adaptive immunity
regulate be cell, macrophage, NK etc function
regulate inflammaton
CD4 (and CD8)
In general, how do cytokines exert their effects?
by producing gene activation
What do interferons do?
Inhibit viral replication
(know type I vs type II?)
interleukins act between what?
leukocytes, duh
(leukocytes are all immune related cells)
side note:
there are therapeutic cytokines and therapeutic blocking cytokines
