Page 625 - Veterinary Immunology, 10th Edition
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FIG. 20.9 Cross-linkage between a BCR and CD32 (an Fc
receptor) by antibody and antigen can turn off a B cell by activating
a phosphatase that in turn blocks signaling by tyrosine kinase.
CD28 and CTLA4 on T cells both bind the same ligand (CD80)
but deliver antagonistic signals. CD28 is an activator, whereas
CTLA4 is an inhibitor. A deficiency of CTLA4 leads to uncontrolled
T cell proliferation and autoimmunity.
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