Immunomodulatory effects of peptide T on Th1/Th2 cytokines

Peptide T is an octapeptide from the V2 region of HIV-1 gp120. It has been shown to resolve psoriatic lesions - an inflammatory skin disease. The mech anisms of anti-inflammatory actions of peptide T are not well understood. T h1 cytokines such as IL-2, and IFN-gamma are upregulated in psoriasis. Thes e cytokines play a key role in the inflammatory and proliferative processes of psoriasis. The effects of peptide T on Th1 and Th2 cytokines were studi ed in order to elucidate the mechanisms of antiinflammatory actions of pept ide T. It was observed that peptide T at 10(-8) M induces IL-10 production by the human Th2 cell line and PBMC (P < 0.05, ANOVA). Also peptide T at 10 (-9) M concentration significantly inhibited IFN-gamma production by PBMC ( P < 0.001, ANOVA). Anti IL-10 antibody inhibited the anti-IFN-gamma effect of peptide T (P < 0.05, t-test). Our study shows that peptide T induces IL- 10 production and inhibits IFN-gamma production. IL-10 is a potent anti-inf lammatory cytokine. It inhibits IL-2 and IFN-gamma production from the T ce lls and downregulates the expression of TNF-alpha in the antigen presenting cells. Recently, IL-10 has been shown to resolve psoriatic lesions. The ef fects of peptide T on IL-10 and IFN-gamma production provides a plausible e xplanation for its clinical efficacy in psoriasis. (C) 1999 Published by El sevier Science Ltd on behalf of the International Society for Immunopharmac ology. All rights reserved.