Humoral immunity

Dr.Sameera Haq lecture

1. Humoral ImmunityHumoral Immunity

2. Is the aspect of immunity that is mediated Is the aspect of immunity that is mediated
by antibodies produced by Plasma cellsby antibodies produced by Plasma cells

3. The production of antibody involves three The production of antibody involves three
distinct phases distinct phases
1 Induction phase:1 Induction phase: Ag reacts with Ag reacts with
specific T and B cells specific T and B cells
2 Expansion and Differentiation 2 Expansion and Differentiation
phase:phase: Lymphocyte clones Lymphocyte clones
proliferate and mature proliferate and mature
to a to a functional stagefunctional stage
3 Effector phase:3 Effector phase: Antibodies exert Antibodies exert
biological effects biological effects

4. 1 B cells recognize antigen via surface 1 B cells recognize antigen via surface
antibody (B cell receptor)antibody (B cell receptor)
2 Ag is internalized , processed and 2 Ag is internalized , processed and
expressed on the surface of the B-cell expressed on the surface of the B-cell
(and other APCs) in association with (and other APCs) in association with
MHC II moleculesMHC II molecules
3 Antigen is recognized by T-helper cells 3 Antigen is recognized by T-helper cells
(CD4+) (CD4+)
4 T cells are activated and differentiated 4 T cells are activated and differentiated
into TH2 cellsinto TH2 cells

5. 5 The stimulated T-cells then release 5 The stimulated T-cells then release
lymphokines that act upon "primed" B-lymphokines that act upon "primed" B-
cells (B-cells that have already cells (B-cells that have already
encountered antigen), inducing B-cell encountered antigen), inducing B-cell
proliferation and differentiation into proliferation and differentiation into
Plasma cellsPlasma cells
6 Plasma cells begin to secrete IgM6 Plasma cells begin to secrete IgM

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
•Low in Magnitude
•Short Lived
•IgM
Secondary Response:
Rapid in Onset
High in Magnitude
Long Lived
IgG (Or IgA, or IgE

10. Monoclonal AntibodiesMonoclonal Antibodies
Recognize only one epitope on an Recognize only one epitope on an
antigenantigen
Polyclonal AntibodiesPolyclonal Antibodies
Recognize multiple epitopes on any one Recognize multiple epitopes on any one
antigenantigen

11. Functions of AntibodiesFunctions of Antibodies
11Bind to and neutralize toxins —basis of Bind to and neutralize toxins —basis of
Passive ImmunizationPassive Immunization
22Bind to and agglutinate pathogens Prevent Bind to and agglutinate pathogens Prevent
them from entering or damaging the cellsthem from entering or damaging the cells
33Opsonize pathogensOpsonize pathogens
44Cause complement dependent killingCause complement dependent killing
55Mediate ADCCMediate ADCC
66Provide passive immunity to fetusProvide passive immunity to fetus

13. Disease DiagnosisDisease Diagnosis
1 Demonstration of Antibodies against a 1 Demonstration of Antibodies against a
specific pathogen is diagnostic of that specific pathogen is diagnostic of that
disease eg viral and bacterial diseases disease eg viral and bacterial diseases
Basis of serological testsBasis of serological tests
2 Detection of Autoantibodies in 2 Detection of Autoantibodies in
autoimmune diseasesautoimmune diseases

14. Therapeutic ApplicationsTherapeutic Applications
Targeted monoclonal antibody therapy is Targeted monoclonal antibody therapy is
employed to treat diseases such as employed to treat diseases such as
rheumatoid arthritis, multiple sclerosis, rheumatoid arthritis, multiple sclerosis,
psoriasis, and many forms of cancer psoriasis, and many forms of cancer
Treatment of Immune Deficiency diseases Treatment of Immune Deficiency diseases
by Passive Immunization (human serum) by Passive Immunization (human serum)
Use of Anti-RhD antibodies to prevent Use of Anti-RhD antibodies to prevent
Hemolytic Disease of NewbornHemolytic Disease of Newborn