Immunoglobulin E and G4 antibodies to infective larvae in a Wuchereria bancrofti endemic population.

IgE and IgG4 antibodies to infective larval antigen of W. bancrofti were measured by ELISA in filarial sera. IgE level was quite high in both infected and non-infected people living in filariae-endemic regions compared to people from non-endemic yet tropical regions. It was also demonstrated that IgE levels in amicrofilaraemic, normal children were lower compared to those of adults. Similarly IgG4 response in children was found to be reduced. The distribution of skin test (immediate hypersensitivity) reaction to larval antigen was not very extensive in people from endemic regions. Higher proportions of the normal population (39%) exhibited skin test reaction than either asymptomatic microfilaraemics or chronic patients (13% each). Specific IgG4 antibody was highly elevated in the sera of people with asymptomatic microfilaraemia. The rate of IgG4 seropositivity was 83% in microfilaraemic individuals compared to 20% in the normal population.