In the present study we focused on effect of ethyl acetate fraction purified from stylissa carteri a marine sponge collected from Andaman on human Blood PBMC and skin keratinocytes from psoriasis patients. The ethyl acetate fraction of stylissa carteri, a marine sponge collected from Andaman and nicobar islands, was found to exhibit decreased human skin keratinocyte count and human PBMC count in Blood. We also observed the elevation of keratinocyte count as well as PBMC count in various in vitro mitogens such as Con A, PHA, PMA induced cell proliferative responses of psoriatic humans. The ethyl acetate fraction of stylissa carteri, which then inhibits the immune mediated skin destruction, which occurs in the pathogenesis of psoriatic patients. However, the ethyl acetate fraction of stylissa carteri In vito treatment of psoriatic humans skin cells and PBMC reduced considerably the increase of cell proliferative response comparative to the normal levels. Human PBMC are proven to be valuable research programmed by the study of pathogenic mechanism of this diseases as well as for testing new therapies