ANTIPROLIFERATIVE AND IMMUNOSUPPRESSIVE PROPERTIES OF MICROCOLIN-A, AMARINE-DERIVED LIPOPEPTIDE

The immunosuppressive effects of microcolin A, a lipopeptide extracted from the marine blue green alga Lyngbya majuscula were investigated. Microcolin A suppressed concanavalin A (IC50 = 5.8 nM), phytohemagglut inin (IC50 = 12.5 nM) and lipopolysaccharide (IC50 = 8.0 nM) induced p roliferation of murine splenocytes. Mixed lymphocyte reaction (IC50 = 5.0 nM), anti-IgM (mu-chain specific) (IC50 = 10.0 nM), and phorbol 12 -myristate 13-acetate plus ionomycin (IC50 = 5.8 nM) stimulation of mu rine splenocytes were all similarly suppressed by microcolin A. The in hibitory activity of microcolin A was time-dependent and reversible an d was not associated with a reduction in cell viability. Moreover, mic rocolin A not only inhibited IL-2 production and IL-2 receptor express ion by concanavalin A activated splenocytes, but also suppressed in vi tro antibody responsiveness to keyhole limpet hemocyanin. These result s indicate that microcolin A is a potent immunosuppressive and antipro liferative agent.