Page 568 - Veterinary Immunology, 10th Edition

cells subsequently produce IL-12 and induce IFN-γ production by
VetBooks.ir NK and Th1 cells. Complete activation to the M1 phenotype

requires exposure to this IFN-γ (Fig. 18.13). It is likely that the NK
cell–mediated pathway works in the early stages of an infection,

whereas the Th1-mediated pathway comes into operation later (Fig.
18.14).

FIG. 18.13 The two pathways by which macrophages can be
activated. One involves IFN-γ production by natural killer cells and
is thus an innate pathway. The other is mediated by IFN-γ from Th1
cells and is an adaptive response.

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