THEORIES OF IMMUNOGLOBULIN FORMATION
The current theories of antibody formation are modifications of selective type
theories or of the template theory. Each of these theories has evidence to support it,
but the clonal selection theory seems to be the most widely accepted.
a. Clonal Selection Theory. This theory is based upon the idea that each
individual has a population of committed lymphocytes. Their surfaces contain receptors
determining which antigens they are capable of recognizing. When unstimulated by
antigen, only small amounts of surface IgM and IgD immunoglobulin are found. When
these cells come into contact with that particular antigenic determinant, the cells multiply
and differentiate into a clone of immunoglobulin-producing plasma cells.
b. Template or Instructive Theory. The basic tenet of the template theory is
that antigen penetrates an antibody-forming cell and serves as a template for antibody
synthesis. The result is that globulin is configured complementary to the antigen.
NONSPECIFIC RESPONSES REPRESENT THE BODY'S INITIAL
ENCOUNTER WITH A FOREIGN AGENT
Two nonspecific immune responses worthy of mention are:
a. Inflammation. The inflammatory process is characterized by an increase in
the number of leukocytes at the site of injury, the formation of fibrin in limiting the spread
of bacteria from the invasion site, and increased blood and lymph flow, which dilutes
and flushes away toxic substances.
b. Phagocytosis. Both neutrophils and macrophages are capable of
phagocytosis. Neutrophils are concerned primarily with destruction of extracellular
pathogens while macrophages are involved with the control of microorganisms that are
able to survive intracellular residence and against which neutrophils are ineffective.