humoral immunity Flashcards
Phases of humoral immune responses
T-dependent and T-independent antibody responses
types of b cells?
what Ab are produced (G, M, A)? affinity?
effector B-cells?
t dependent only occur with protein antigens
Features of primary and secondary antibody responses lag after immunization peak response Ab isotype Ab affinity
Antigen receptor-mediated signal transduction in B lymphocytes
Ag binds surface bond Ig to, No APC needed
requires a cluster of receptors bound to the Ag to generate response at BCR complex
will result in a phos cascade that expresses TFs to induce gene epression
Role of innate immune signals in B cell activation, receptors involved?
how is BCR activated?
(A) complement receptor (CR2) binding by C3d bound to microbe.
(B) (B) Toll-like receptor (TLR) binding by PAMP.
both can help form receptor clusters to drive b cell activation
Functional consequences of antigen receptor-mediated B cell activation
changes in these cells?: increased expression in what genes? increased what to interact with T cells? increased expression what receptors? how to migrate out? generation of what kind of cells?
consequences of these changes?
s
Sequence of events in helper T cell-dependent antibody responses
Antigen presentation by B lymphocytes to helper T cells
Activated T cells that recognize antigen presented on B cells use _____ligand and _______ to activate the B cell
Activated T cells that recognize antigen presented on B cells use CD40 ligand and cytokines to activate the B cell
causes B cell dif and prolif for effector functions
The germinal center reaction
Immunoglobulin (Ig) heavy-chain isotype (class) switching pathways, what signals produce the various Ig?
s
principal effector functions of IgM, IgG, IgE, IgA
Mechanism of immunoglobulin heavy-chain isotype switching
repeated exposure to a protein Ag causes creation of what? due to?
Repeated exposure to a protein antigen drives creation of higher affinity antibodies, due to interactions with Tfh
Selection of high-affinity B cells occurs where?
within the germinal centers
Somatic Hypermutation, purpose/enzyme used?
occurs to produce variable affinity Ab and high-affinity Ab, uses AID
AID = activation-induced deaminase is involved; deaminates cytosine (DNA base) to uracil. Sometimes uracil is cleaved (see isotype switching) and repaired by an error-prone mechanism. Even when uracil persists, it results in a base pairing change.
Selection of high-affinity B cells mechanism
FDCs
present antigen via antibodies bound to Fc receptors or complement receptors instead of MHC molecules
Antigens are never internalized by FDCs.
The antibodies are those that were secreted by B cells themselves.
T cell dependent B cell response vs T independent response type of Ag? Isotype switiching? affinity maturation? plasma cells life span? memory cells?
Regulation of the humoral response occurs with?
Ab feedback
Humoral response terminated once sufficient quantities of IgG are produced to result in this combination of binding ona B cell (Ag binds both Ig and Fc receptor)
Effector Mechanisms of Humoral Immunity
IgG effector functions
IgM effector functions
IgA effector function
IgE effector function
Neutralization process of microbes and toxins by antibodies
what can the Ab bind to and what are the effects?
s
Antibody-mediated opsonization and phagocytosis of microbes process
Antibody-dependent cellular cytotoxicity (ADCC) process
Ag displayed on cell surface can be done without MHC, could be a viral protein associated with the membrane instead
. IgE- and eosinophil-mediated killing of helminths process
IgE binds the Ag then bonds Fc receptors of the eosinphils to induce degranulation to kill hemiliths
Complement System
part of which system?
classical pathway begins with?
diagrammed steps
Component of the Innate Immune Response
Classical pathway is part of Adaptive Immune Response
Classical pathway starts with recognition of antigen engaged antibodies by complement C1 protein.
mucosal immunity
done with Transport of IgA through epithelium (produced in lamina propria)
