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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