Humoral immunity is mediated by antibodies produced by plasma cells. It involves three phases: induction, expansion/differentiation, and effector. In the induction phase, antigens react with B and T cells. In the expansion/differentiation phase, lymphocyte clones proliferate and mature. In the effector phase, antibodies exert biological effects such as neutralizing toxins, agglutinating pathogens, and complement-dependent killing. Primary responses are slow with low magnitude and IgM, while secondary responses are rapid with high magnitude and long-lived IgG.
2. Is the aspect of immunity that is mediated
by antibodies produced by Plasma cells
3. The production of antibody involves three
distinct phases
1 Induction phase: Ag reacts with
specific T and B cells
2 Expansion and Differentiation
phase: Lymphocyte clones
proliferate and mature
to a functional stage
3 Effector phase: Antibodies exert
biological effects
4. 1 B cells recognize antigen via surface
antibody (B cell receptor)
2 Ag is internalized , processed and
expressed on the surface of the B-cell
(and other APCs) in association with
MHC II molecules
3 Antigen is recognized by T-helper cells
(CD4+)
4 T cells are activated and differentiated
into TH2 cells
5. 5 The stimulated T-cells then release
lymphokines that act upon "primed" B-
cells (B-cells that have already
encountered antigen), inducing B-cell
proliferation and differentiation into
Plasma cells
6 Plasma cells begin to secrete IgM
6.
7.
8. Types of humoral response
•Primary response:
Begins immediately
Predominantly IgM
Appears 48 to 72 hours later
•Secondary response:
Occurs within 24 to 48 hours
Predominantly IgG.
Persists much longer
Result of repeated contact with
antigens
9. Primary Response:
•Slow in Onset Secondary Response:
•Low in Magnitude Rapid in Onset
•Short Lived High in Magnitude
•IgM Long Lived
IgG (Or IgA, or IgE
10. Monoclonal Antibodies
Recognize only one epitope on an
antigen
Polyclonal Antibodies
Recognize multiple epitopes on any one
antigen
11. Functions of Antibodies
1 Bind to and neutralize toxins —basis of
Passive Immunization
2 Bind to and agglutinate pathogens Prevent
them from entering or damaging the cells
3 Opsonize pathogens
4 Cause complement dependent killing
5 Mediate ADCC
6 Provide passive immunity to fetus
12.
13. Disease Diagnosis
1 Demonstration of Antibodies against a
specific pathogen is diagnostic of that
disease eg viral and bacterial diseases
Basis of serological tests
2 Detection of Autoantibodies in
autoimmune diseases
14. Therapeutic Applications
Targeted monoclonal antibody therapy is
employed to treat diseases such as
rheumatoid arthritis, multiple sclerosis,
psoriasis, and many forms of cancer
Treatment of Immune Deficiency diseases
by Passive Immunization (human serum)
Use of Anti-RhD antibodies to prevent
Hemolytic Disease of Newborn