Page 446 - Veterinary Immunology, 10th Edition

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FIG. 15.11 The stimulation of B cells through the CD21/CD19
complex. CD21 binds to C3d on the antigen. Signaling through
CD19, it generates a potent costimulatory signal to enhance B cell
responses.

The B cell Fc receptor, FcγRIIb, is a negative regulator of B cell
function. When an IgG molecule binds and links this receptor to a
BCR through antigen, it inhibits antibody formation. This has

important practical consequences when vaccinating young animals
(Chapter 25).

Toll-Like Receptors and PAMP Help

Although BCR-antigen-binding plus T cell co-stimulation trigger
initial B cell division, they cannot induce a prolonged, self-
sustaining B cell response. Complete activation of B cells also
requires coordinated signals from their toll-like receptors (TLRs).

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