BANCROFTIAN FILARIASIS IN KWALE DISTRICT OF KENYA .3. QUANTIFICATION OF THE IGE RESPONSE IN SELECTED INDIVIDUALS FROM AN ENDEMIC COMMUNITY

One hundred and sixty-two individuals from a community in Kwale Distri ct, Kenya, endemic for bancroftian filariasis, were selected for a stu dy on the IgE response to filarial antigen (prepared from adult Brugia pahangi). Following clinical and parasitological examination, the ind ividuals were grouped into different categories, based on the presence /absence of microfilaraemia, the presence/absence of acute or chronic (hydrocele or elephantiasis) clinical manifestations, and age. The tot al and filarial-specific IgE responses were evaluated in all individua ls, and the responses in the various categories were compared with eac h other and with the responses of control groups of individuals from f ilariasis-free areas. The majority of individuals from the endemic are a had highly elevated serum concentrations of total IgE. Overall and w ithin each clinical category, the concentration of total IgE was highe r in those individuals from the endemic area who had microfilaraemias than in those that did not. The majority of individuals from the filar iasis endemic area also had significantly elevated levels of filarial- specific IgE. In contrast, the concentration of specific IgE was lower in subjects with microfilariae than in those without, irrespective of their clinical status. Only a small proportion of total IgE was filar ial-specific, the mean value varying from 0.4% to 9.8%, depending on c ategory. Among the endemic individuals, the mean proportion of total I gE which was filarial-specific was 3.6 times higher in the microfilari a-negative than in the microfilaria-positive, indicating that much of the filarial-induced IgE in microfilaraemic individuals could be non-s pecific. No clear relationship was observed between the IgE response a nd the clinical manifestations or age of the endemic individuals. A ro le for IgE in the regulatory response to filarial infection is suggest ed.