IMMUNITY TO ONCHOCERCIASIS - PUTATIVE IMMUNE PERSONS PRODUCE A TH1-LIKE RESPONSE TO ONCHOCERCA-VOLVULUS

Immunity to Onchocerca volvulus (Ov) infection is suggested by the pre sence of putatively immune (PI) subjects in a region of Ecuador in whi ch Ov is endemic. PI subjects were identified by traditional diagnosti c methods combined with a polymerase chain reaction-based assay for Ov DNA in skin snips. Responses of peripheral blood mononuclear cells (P BMC) from the PI group (n = 16) were compared with those of persons wi th active infection (microfiladermic [MF] subjects; n = 51). PBMC of P I subjects proliferated significantly more to Ov antigen (OvAg; P < .0 09) than did PBMC of MF persons but less to streptolysin-O (P < .001). Cytokine analysis of PBMC culture supernatants revealed that PI subje cts (n = 11) produced significantly more interferon-gamma to OvAg than did those in the MF group (n = 18; P = .018), less interleukin (IL)-5 to nonparasite antigen (P = .003) and mitogen (P = .012), and less IL -10 spontaneously (P = .016). Thus, immunity to Ov may in part be medi ated by an antigen-specific Th1-type response.