Page 619 - Veterinary Immunology, 10th Edition
P. 619
VetBooks.ir Duration of Tolerance
The duration of tolerance depends on antigen persistence and on
the ability of the bone marrow to generate fresh T or B cells. Once
an antigen is completely eliminated, tolerance fades. If, however,
the antigen is persistent, such as occurs with an animal's own self-
antigens, tolerance also persists. In the continued presence of an
antigen, newly formed antigen-sensitive cells will undergo
apoptosis as soon as their receptors bind self-antigen. Treatment
that promotes bone marrow activity, such as low-dose X-
irradiation, hastens the fading of tolerance, whereas
immunosuppressive drug treatment has the opposite effect.
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