Serum immune complexes as diagnostic and therapeutic markers in lymphatic filariasis.

In the present study we examined the utility of measuring antigen-specific soluble immune complexes (ICs) for the differential diagnosis and therapeutic monitoring of Bancroftian filariasis. Antigen-specific ICs were detected in significantly elevated levels in 90% of lymphatic filarial subjects suffering from disease manifestations, and very low levels in 8-10% of microfilaria (MF) carriers. The high incidence of antigen-specific ICs in the circulation of filarial subjects with clinical manifestations in contrast to the negligible presence in MF carriers facilitates serological differentiation of these two important stages of lymphatic filarial infection. A sudden spurt in circulating levels of antigen-specific ICs was recorded in all MF carriers on diethylcarbamazine (DEC) therapy, and the magnitude of the increase correlated positively with the pretreatment levels of circulating MF. Thus, it is evident from the present study that circulating ICs (CICs) are potential serological markers for both the differential diagnosis of filarial infection and therapeutic monitoring of MF carriers.