INTERFERON-GAMMA PRODUCTION BY PERIPHERAL-BLOOD MONONUCLEAR-CELLS FROM RESIDENTS OF AN AREA ENDEMIC FOR SCHISTOSOMA-MANSONI

During human schistosomiasis host responses to antigens of various par asite life-cycle stages may contribute to whether the severe, hepatosp lenic state develops or the patient remains relatively asymptomatic th roughout infection, and may play a role in resistance. This study eval uated production of interferon gamma (IFN-gamma) in vitro by schistoso me antigen-stimulated peripheral blood mononuclear cells (PBMCs) from asymptomatic patients, and by PBMCs from apparently uninfected, untrea ted persons living in areas endemic for Schistosoma mansoni ('endemic normals'). IFN-gamma production parallels PBMC proliferation in that s chistosomal egg antigens stimulate patent patients' cells poorly, but strongly stimulate PBMCs from 'endemic normals'. This is proportionall y true for antigens from adult worms and cercariae. Although asymptoma tic patent patients' cells produced little or no IFN-gamma in response to the 3 schistosomal antigenic extracts, their PBMCs, and PBMCs from 'endemic normals', produced expected amounts of IFN-gamma when expose d to phytohaemagglutinin. This implies that persons with patent infect ions have schistosome antigen-specific defects in their ability to res pond to IFN-gamma production that are not exhibited by putatively resi stant 'endemic normals'.