Page 431 - Veterinary Immunology, 10th Edition

The division of the adaptive immune system into two major
VetBooks.ir components is based on the need to recognize two distinctly

different forms of foreign invaders. Some invaders enter the body
and grow in extracellular fluids. These “exogenous” invaders are

destroyed by antibodies. Other invaders grow inside cells, where
antibodies cannot reach. They are destroyed by T cell-mediated
responses. Antibodies are produced by the lymphocytes called B
cells. This chapter describes B cells and their response to antigens.

B cells are found in the cortex of lymph nodes, in the marginal
zone in the spleen, in the bone marrow, throughout the intestine,
and in Peyer's patches. Few B cells circulate in the blood. Like T
cells, B cells have a large number of identical antigen-binding

receptors on their surface. Each B cell, therefore, can only bind and
respond to a single antigen. Antigen receptors are generated at
random during B cell development in a process described in
Chapter 17. If a B cell encounters an antigen that binds its receptors,

it will, with appropriate co-stimulation, respond by secreting its
receptors into body fluids, where they are called antibodies.

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