Protein Protocols Protein Protocols

Antibody Production 935
128
Antibody Production
Robert Burns
1. Introduction
Antibodies are proteins that are produced by the immune systems of animals in
response to foreign substances. The immune system has the ability to recognize material
as nonself or foreign and mount a response to them. Substances that elicit this are
known as immunogens or antigens, and one of the outcomes of the immune response is
the production of antibodies that will recognize and bind to the eliciting substance.
The immune response results in the degradation of the antigen by cells called macrophages
and its presentation in fragments to B lymphocytes that are found in the lymphatic
tissues of the animal. On presentation of the antigen fragments the B lymphocytes
mature and “learn” to produce antibody molecules that have a specific affinity to the
antigen fragment that they have been presented with. This process gives rise to populations
of B lymphocyte clones each of which produces antibody molecules to different
locations known as epitopes on the target antigen (1). As individual clones produce the
antibody molecules and there are many of them, the resulting antibody mix in the blood
is known as polyclonal and the fluid derived from the clotted blood is known as
polyclonal antiserum.
Artificial exposure to antigens to produce antibodies in animals is known as immunization,
and repeated exposure leads to a condition known as hyperimmunity, in which
a significantly large proportion of the circulating antibodies in the animals blood will
be directed toward the antigen of interest. Immunization gives rise to stable but quiescent
populations of B lymphocytes known as memory cells that will respond to the
presence of the antigen by dividing to increase their number and the level of circulating
antibody in the blood.
The primary exposure to an antigen gives rise to a pentameric form of antibody
known as immunoglobulin M (IgM). Subsequent exposure to the antigen causes a shift
in the antibody type to the more stable immunoglobulin G (IgG). This shift in antibody
type happens as affinity maturation of the B lymphocyte clones occurs.
Some antigens, particularly highly glycosylated proteins, do not elicit the production
of memory B lymphocytes and also may not give rise to IgG antibodies even after
repeated immunization. These are known as anamnestic antigens, and as no memory
B lymphocytes are produced, the immune system always interprets exposure to them
From: The Protein Protocols Handbook, 2nd Edition
Edited by: J. M. Walker © Humana Press Inc., Totowa, NJ
935