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 Somatic mutation B not recognizing Ag on FDC die by apoptosis High-affinity plasma and memory cells leave germinative center Selection

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 response Secondary response Amounth of antibody

IgM Humoral immune response to thymus-independent antigens Encapsulated bacteria B-cell

Cells that respond to thymus-independent antigens Spleen

extarcellular microorganisms and their toxinsj.Phenomenon of inhibition of antibody production by antibody bound to antigen is 10. follicular B-cells i.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 ___9.____8.___7.___6.____5.____4.____3.____2.____1.____ fjgbaidech