Cellular and Molecular basis of Immunity

1. Atifa Ambreen
M.Phil, Microbiology
Government College University, Faisalabad

2. • The immune system consists of cellular components
and molecular components that work together to
destroy antigens (Ags).
• The main cellular components of the immune system
are the phagocytes and the lymphocytes. The
phagocytes comprise the polymorphonuclear
leucocytes and the macrophages.
• The antibodies are the main component of the
humoral (non-cellular) immune response, a part of
the adaptive immune response. Antibodies are
basically receptors; they are proteins that can bind to
antigens

6. Antibody Classes
IgM- It is the first antibody
to appear in the response to
initial exposure to an antigen.
Expresses on the surface of B
cells (monomer) and in a
secreted form (pentamer) with
very high avidity. Eliminates
pathogens in the early stages
of B cell-mediated (humoral)
immunity before there is
sufficient.

7. • IgG-Found in mucosal areas, such as the gut,
respiratory tract and urogenital tract, and
prevents colonization by pathogens. Also found
in saliva, tears, and breast milk. IgG is a
type of antibody. Representing approximately
75% of serum antibodies in humans, IgG is the
most common type of antibody found in blood
circulation. IgG molecules are created and
released by plasma B cells. Each IgG has
two antigen binding sites.

8. IgE-Binds to allergens and triggers histamine
release from mast cells and basophils, and
is involved in allergy. It protects against
parasitic worms. IgE is synthesised by
plasma cells. IgE's main function is immunity
to parasites like Schistosoma mansoni,
Trichinella spiralis, and Fasciola hepatica. IgE
has main role in hypersensitivity.

9. • IgD- functions mainy as an antigen receptor
on B cells that have not been exposed to
antigens. It has been shown to activate
basphils and ast cells to produce antimicrobial
factors. It is an antibody isotype that mkes up
about 1% of proteins in the plasma
membranes of immature B-lymphocytes
where it is usually co-expressed with another
cell surface antibody called IgM.

10. IgA-Found in mucosal
areas, such as the gut,
respiratory tract and
urogenital tract, and
prevents colonization by
pathogens. is an antibody
that plays a crucial role in the
immune function of mucous
membranes. The amount of
IgA produced in association
with mucosal membranes is
greater than all other types
of antibody combined.
Represents up to 15% of
total immunoglobulins
produced throughout the
body.