T helper type 1 development of naive CD4+ T cells requires the coordinate action of interleukin-12 and interferon-gamma and is inhibited by transforming growth factor-beta.
It was observed in vitro and in vivo that both interferon (IFN)-gamma and interleukin (IL)-12 can promote the development of T helper type 1 (TH1) cells. Since IL-12 was shown to be a costimulator for the production of IFN-gamma by T or natural killer (NK) cells, IL-12 might play only an indirect role in TH1 differentiation by providing IFN-gamma which represents the essential differentiation factor. Using anti-CD3 monoclonal antibody (mAb) for activation of naive CD4+ T cells in the absence of accessory cells we could demonstrate that costimulation by IFN-gamma alone results only in marginal TH1 development. Similarly, IL-12 in the absence of IFN-gamma is only a poor costimulator for inducing differentiation towards the TH1 phenotype. Our data indicate that both cytokines are required to allow optimal TH1 development and that IL-12 has a dual role, it promotes differentiation by direct costimulation of the T cells and also enhances the production of IFN-gamma which serves as a second costimulator by an autocrine mechanism. Another cytokine that was reported to favor TH1 differentiation in certain experimental systems is transforming growth factor (TGF)-beta. With naive CD4+ T cells employed in this study TGF-beta strongly inhibited the production of IFN-gamma triggered by IL-12 as well as the IL-12-induced TH1 development. When TGF-beta was combined with anti-IFN-gamma mAb for neutralization of endogenous IFN-gamma the TH1-inducing capacity of IL-12 was completely suppressed.
Schmitt
E
E
Institut für Immunologie, Mainz, FRG.
Hoehn
P
P
Huels
C
C
Goedert
S
S
Palm
N
N
Rüde
E
E
Germann
T
T
D000818:Animals; D005260:Female; D007371:Interferon-gamma / Q000096:biosynthesis / Q000494:pharmacology*; D018664:Interleukin-12; D007378:Interleukins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D006377:T-Lymphocytes, Helper-Inducer / Q000187:drug effects* / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D007378:Interleukins; D016212:Transforming Growth Factor beta; D018664:Interleukin-12; D007371:Interferon-gamma