Page 414 - Veterinary Immunology, 10th Edition

FIG. 14.14 Major differences between Th1 and Th2 populations.
VetBooks.ir are the set of effector cytokines they secrete.
Note that the polarizing cytokines that trigger them are different, as

FIG. 14.15 Different antigens can trigger distinctly different Th cell
subpopulations. For example, T cells exposed to a parasite antigen
from the roundworm Toxocara canis mount a type 2 response and
secrete IL-4 and IL-5. In contrast, T cells exposed to PPD, an
antigen from Mycobacterium tuberculosis, mount a type 1 response
characterized by secretion of IFN-γ and IL-2. (From Del Prete G, De Carli
M, Mastromauro C, et al: Purified protein derivative of Mycobacterium tuberculosis
and excretory-secretory antigen(s) of Toxocara canis expand in vitro human T cells
with stable and opposite (type 1 T helper or type 2 T helper) profile of cytokine
production, J Clin Invest 88:346-350, 1991.)

Interferon-γ

Interferon-γ has some antiviral activity, but its major function is the

regulation of Th1 cell responses (Fig. 14.16). IFN-γ is mainly
+
produced by Th1 cells, CD8 cytotoxic T cells, and natural killer
(NK) cells, with lesser amounts from antigen-presenting cells, B
cells, and natural killer T (NKT) cells (Chapter 19). It activates cells

through the JAK-STAT pathway. It promotes macrophage
activation, suppresses Th2 cells, and enhances NK cell activity (Box

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