Antigens responsible for eosinophil hyporesponsiveness in Brugia pahangi microfilariae injected mice

In order to identify the eosinophil hyporesponsiveness factor in the microfilaremic host, stage-specific monoclonal antibodies against microfilariae (Mf) of Brugia pahangi were produced. One of these (MfG2a) was established for the first time as a monoclonal antibody of IgG2a isotype against Mf. MfG2a recognizes the eosinophil hyporesponsiveness factor, the 42 kDa excretory/secretory antigen of Mf. Treatment of MfG2a significantly ( P < 0.05) induced eosinophil response with rapid reduction of microfilaremia in previously Mf injected mice which became amicrofilaremic within 2 weeks. Eosinophil hyporesponse was observed in the control microfilaremic mice and the microfilaremia persisted at high levels. Another monoclonal antibody, MfG1 of the IgG1 class, recognized the 64-kDa surface antigen of Mf, MfG1 was less effective in eosinophil response- or microfilaremia reduction. These data suggest that the 42-kDa microfilarial excretory/secretory antigen might be responsible for the eosinophil hyporesponsiveness in B. pahangi Mf injected mice.