Humoral immunity

1. DEVELOPMENT AND WORKING OF
HUMORAL IMMUNITY
BY AMISHA KUMARI
ROLL NO. – 111
BATCH – 35TH
KMC KATIHAR

2. INTRODUCTION
Humoral immunity is defined as the immunity medicated by antibodies, which are secreted by
B lymphocytes.
2 B lymphocytes secreted the antibodies into blood and lymph.
3 As in the case of cell – medicated immunity, the macrophages and other antigen presenting
cells plays an important role in the development of humoral immunity.
3
4
Since the B lymphocytes provides immunity through humors, this type of immunity is called
humoral immunity of B cell immunity.

3. working of Humoral Immunity
• Presentation of antigen.
• Activation of B cells.
• Differentiation of B cells into plasma cells.
• Proliferation of plasma cells and antibody
production.
• Killing of the invaders by antibodies that include
activation of complement system.
• Formation of memory B cells and subsequent
immunological responses.
Activation of humoral immunity involves 6 steps
working of Humoral Immunity

4. Presentation of antigen
: - APCs in humoral immunity
include B cells themselves.
: - Antigen combined with MHC II
molecules on the surface of APC
(Ag-MHC complex).
: - When an antigen binds directly to
the receptors present on the
surface of the B cells, the B cells
are activated.
: - the process of activation is
accentuated by the co-stimulation
from type 2 helper cells.
Activation of B cells

5. Differentiation of B cells into plasma cells
The activated B cells enlarges in size that undergoes special differentiation, which is a
kind of complete transformation to become a separate cell, called plasma cell.
The B cell is transformed completely in structure and function.
First the B cell enlarges in size and then undergoes many changes.
The enlarged B cell appears almost like a lymphoblast called B
immunoblasts.
Co-stimulation by T-helper cells.
Plasma cell has abundant reticulam and golgi complex.
Proliferation of plasma cells and antibody production :- plasma cells secrete a
large quantity of antibodies.

6. Killing of the invaders
Neutralizing antigen :- Antibodies neutralize the antigens. For example:- antigens detoxify
the bacterial toxins and prevent them to induce immunological reaction
Immobilization of microbes :- Antibodies prevent the motility of bacteria thereby inhibit
their spread to the surrounding tissue.
Activation of complement system :- Antibodies activates the classical pathway of
complement system.
Precipitation of antigens:- Antibodies cause agglutination and
precipitation of antigens.
Facilitation of phagocytosis :- Antibodies enhance phagocytosis by
opsonizing the antigen.
Providing immunity in newborns:- IgG and IgA.
Antibodies attack antigen and kill organisms (destroy antigens) by following 6
mechanisms

7. Formation of memory B cells and subsequent immunological
responses
• A small sunset of activated B cells
differentiates into memory cells.
• memory B cells normally remain inactivate,
unless stimulated by the similar antigens.

8. TYPES OF HUMORAL RESPONSES
Primary Response Secondary Response
• When the same antigen enters the body for the second
time, the immune response triggered is the secondary
response.
• Occurs speedily and intensely, which is due to the
immunological memory.
• Antibodies are formed rapidly. Therefore,
concentration of antibody rise fast and reaches a
greater peak.
• Antibody never returns to normal rather remains
elevated for a longer duration.
• The antibodies in the secondary response are
primarily of IgG type.
When antigens enters into the body for the first time, the
immunological response induced is called primary
response.
The antibodies are formed slowly with a latent period of
about 4 days to 4 weeks.
The concentration of antibodies rises gradually and
attains a smaller peak.
Though, IgM and IgG antibodies contribute to the primary
response, the response is mainly due to IgM.
It returned back to normal within few days to weeks.

10. Thankyou
BY AMISHA KUMARI
ROLL NO. – 111
BATCH – 35TH
KMC KATIHAR