Immunomodulatory effects of peptide T on Th 1/Th 2 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 mechanisms of anti-inflammatory actions of peptide T are not well understood. Th1 cytokines such as IL-2, and IFN-γ are upregulated in psoriasis. These cytokines play a key role in the inflammatory and proliferative processes of psoriasis. The effects of peptide T on Th1 and Th2 cytokines were studied in order to elucidate the mechanisms of antiinflammatory actions of peptide 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-γ production by PBMC (P<0.001, ANOVA). Anti IL-10 antibody inhibited the anti-IFN-γ effect of peptide T (P<0.05, t-test). Our study shows that peptide T induces IL-10 production and inhibits IFN-γ production. IL-10 is a potent anti-inflammatory cytokine. It inhibits IL-2 and IFN- γ production from the T cells and downregulates the expression of TNF-α in the antigen presenting cells. Recently, IL-10 has been shown to resolve psoriatic lesions. The effects of peptide T on IL-10 and IFN-γ production provides a plausible explanation for its clinical efficacy in psoriasis. Copyright (C) 1999.