Cyperus scariosus Chloroform Fraction Inhibits T cell Responses in Balb/C Mice

Purpose: To investigate the T cell inhibition potential of 50% ethanol extract of Cyperus scariosus (CS) and its bioactive chloroform fraction (CSC). Methods: The preliminary screening of the extract was carried out by humoral antibody response and delayed-type hypersensitivity models employing sheep red blood cells (SRBC) as the antigen. Further, the extract was studied by skin allograft rejection test, and phagocytosis - in vitro and ex vivo - by C. albicans method and carbon clearance test, respectively. The extract was fractionated with chloroform, n-butanol and water, and then used to investigate the T-cell specific immunosuppressive potential of these fractions by flow cytometry. Results: On p.o. administration, CS inhibited both humoral and cell-mediated immune responses significantly (p < 0.01) by suppressing primary (26.8 %) and secondary (29.7 %) antibody titres, and also inhibited cell-mediated delayed type hypersensitivity (DTH) immune response (45.9 %) at 600 mg/kg dose, phagocytosis - both in vitro (37.4 %) and ex vivo (37.8 %) - and delayed the graft rejection time (45.8%), thus confirming marked immunosuppression. Out of the three isolated fractions, only the chloroform fraction significantly (p < 0.01) suppressed CD8+/ CD4+ T cell surface markers (14.0/25.3 %) and intra-cellular Th1 cytokines, viz, IL-2 (34.4 %), and IFN-γ (34.7 %), compared to cyclosporine-A (5), a standard T cell inhibitor (53.6 %) which was given to Balb/C mice at 200 mg/kg dose. CSC did not significantly (p < 0.01) suppress Th2 (IL-4) system. Conclusion: The findings from this investigation reveal that C. scariosus causes immunosuppression by inhibiting Th1 cytokines