Abstract: Objective To investigate Th1/Th2 pattern of response in psoriasis and to study the effects of CTLA4Ig on Th1/Th2 shift in psoriasis. Methods The levels of IL-2, IFN-γand IL-4 were assessed by ELISA in the supernatant of cultured peripheral blood mononuclear cells (PBMCs) from 33 patients with psoriasis vulgaris and 20 healthy blood donors. Cytokine synthesis was induced by activation with phytohemagglutinin (PHA) and staphylococcal enterotoxin B (SEB) with or without CTLA4Ig. Results Levels of IL-2, IFN-γand IL-4 were markedly increased by PBMCs from psoriatic patients incubated with SEB (P<0.01). The ratio of IFN-γ/ IL-4 was significantly higher in active stage of psoriasis than that in static stage (P<0.01). CTLA4Ig inhibited the secretion of IL-2 and IFN-γin a dose dependent manner. IL-4 production was relatively enhanced in comparison with IL-2 and IFN-γ. The secretion of the three cytokines was significantly suppressed when the dose of CTLA4Ig increased to 10 μg/ml. Conclusion Th1 type predominates in psoriasis. CTLA4Ig could down regulate Th1 cytokines and up regulate Th2 cytokines, which indicate that CTLA4Ig could switch T cell responses of from Th1 to Th2 in psoriasis.

Key words: Psoriasis, Chimeric proteins, Th1 cells, Th2 cells, Interleukin 2, Interleukin 4, Interferon type Ⅱ