Humoral immune response
Type of adaptive immune response mediated by
antibodies that neutralize and eliminate extracellular
pathogens and their toxins
Cell mediators of humoral immunity are B lymphocites
Functions of antibodies
Humoral immune response
Thymus-dependant
(T-dependant)
Thymus-independant
(T-independant)
Cells that respond to thymus-dependent antigens
Spleen,other lymphoid organs
Functional consequences of B-cell activation
Phases of humoral immune response
Interaction of helper T- cells and B-cells in peripheral lymphoid tissues
Antigen recognition and presentation by B-cells
Interaction of helper T- cells and B-cells in peripheral lymphoid tissues
T- and B-cell cooperation
Antibody affinity maturation
• Process of increasing the affinity of the antibody in prolong or repeated exposure to the same antigen
• It takes place in germinative centers of lymphoid follicules
• Underlying mechanism is:
– somatic mutation of gene for variable region of Ig in proliferating B-cells and selection of B-cells with high-affinity receptor for that antigen
Activated B go to germinative center
Intensive proliferation
Hypermutation of Ig V genes
Somatic hypermutations of Ig V genes
Activated B go to germinative center
Intensive proliferation
Hypermutation of Ig V genes
B recognizing Ag on FDC survive
Som
ati
c m
uta
tion
B not recognizing Ag on FDC die by apoptosis
High-affinity plasma and
memory cells leave germinative center
Sele
cti
on
Regulation of humoral immune response
• Process where Ab bound to Ag inhibits further Ab production
• Purpose: humoral immune response termination upon sufficient IgG production
Antibody feed-back regulation
Mechanism of feed back regulation by Abs
Antibody feed-back regulation
• In therapy of some autoimmune inflammatory diseases
IgG of numerous donors (IVIG)- engage inhibitory FcR on B-cells and inhibit pathological immune response
Clinical application
Primary and secondary humoral immune response
First exposure to the antigen
Repeated exposure to the antigen
Primary responseSecondary response
Am
ounth
of
an
tibody
IgM
Humoral immune response to thymus-independent antigens
Encapsulated bacteria
B-cell
Cells that respond to thymus-independent antigens
Spleen
extarcellular microorganisms and their toxins j.Phenomenon of inhibition of antibody production by antibody bound to antigen is
10.
follicular B-cellsi.Secondary humoral immune response, compared to primary , is
9.
antibody feed-back regulationh.Features of humoral immune response to thymus-dependent antigens are
8.
thymus-independentg.Humoral immune response to protein antigens necessary is the participation of
7.
antibodiesf.Cells that respond to proteins are6.
isotype switch, affinity matturation and memory B-cell development
e.In response to thymus-independent antigens mostly is produced
5.
CD4+ T-cellsd.Cells that respond to polysaccharides in blood are
4.
quantitatively and qualitatively different (faster, stronger and more efficient)
c.Humoral immune response to non-protein antigens is
3.
B-cells of marginal zone in spleenb.Humoral immune response is important in defense aginst
2.
IgMa.Adaptive humoral immune response is mediated by
1.
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