AN EXTRACT OF THE FERN POLYPODIUM-LEUCOTOMOS INHIBITS HUMAN PERIPHERAL-BLOOD MONONUCLEAR-CELLS PROLIFERATION IN-VITRO

An alcoholic extract of the fern Polypodium leucotomos (PLE) has been empirically used as an immunosuppressor for the treatment of several a utoimmune diseases. In this paper, we investigated the effects of PLE on activation and proliferative responses of peripheral blood mononucl ear cells (PBMNC) from healthy donors to T lymphocyte polyclonal mitog ens. PLE shows a significant inhibitory effect on the proliferative re sponse of PBMNC to stimulation with phytohaemagglutinin (PHA) or anti CD3 monoclonal antibodies (P < 0.05). In contrast, PLE did not modify the proliferative response of PBMNC to phorbol esters (P > 0.05). The inhibitory effect of PLE upon mitogen induced PBMNC proliferation is t ime dependent and can be overcome by the exogenous addition of interle ukin-2 to the culture medium (P < 0.05). The decreased proliferative r esponse of PBMNC to PHA stimulation in the presence of PLE is not asso ciated with a significant modification of expression of the alpha chai n (CD25) of the IL-2 receptor (P > 0.05). In conclusion, PLE shows an inhibitory effect on the polyclonal proliferative response of PBMNC to T Lymphocyte mitogens that interact with cytoplasmic membrane molecul es. (C) 1997 International Society for Immunopharmacology.