Page 631 - Veterinary Immunology, 10th Edition

VetBooks.ir

FIG. 20.13 The origins and properties of transforming growth
factor-β.

TGF-β regulates macrophage activities. It may be either
inhibitory or stimulatory, depending on the presence of other

cytokines. Thus it can enhance integrin expression as well as
phagocytosis by blood monocytes. On the other hand, it suppresses
the respiratory burst and NO production and blocks monocyte
differentiation and the cytotoxic effects of activated macrophages.
TGF-β is required for optimal dendritic cell development and

regulates the interaction between follicular dendritic cells and B
cells. TGF-β inhibits T and B cell proliferation and stimulates their
apoptosis. Apoptotic T cells release TGF-β, contributing to the

suppressive environment. TGF-β influences the differentiation of
Th subsets. It tends to promote Th1 responses and the production of
IL-2 in naïve T cells, but it also antagonizes the effects of IFN-γ and
IL-12 in memory cells. It also controls the development and
differentiation of B cells, inhibiting their proliferation, inducing

apoptosis, and regulating IgA production.

631