Detection of IgE antibodies in onchocerciasis. Possibility of using allergens from Dipetalonema viteae extracts that cross-react with allergenic determinants in crude extracts of Onchocerca volvulus.

The present study reports the presence of Onchocerca volvulus specific IgE in the sera obtained from onchocerciasis patients. About 70% of onchocerciasis patients showed a raised level of O. volvulus specific IgE compared to patients infected either with other human filarids (Loa loa, Wuchereria bancrofti, Brugia malayi) or with other helminths (Schistosoma mansoni, Ascaris lumbricoides, Fasciola hepatica). The O. volvulus specific IgE level was significantly higher in patients exhibiting 'gale filarienne' than in microfilaremic patients or in endemic controls. The total IgE level was significantly raised in the serum samples of all groups of subjects from endemic areas compared to European controls. There was no significant increase in the level of IgE in the onchocerciasis sera when O. volvulus antigen was replaced by the antigens from various helminths in the present assay system (radioallergosorbent test). However, there was a clear evidence of the presence of cross-reacting allergens in the crude extracts from adults of O. volvulus and Dipetalonema viteae (a rodent filarial parasite) because there was a significant reduction in IgE level in onchocerciasis sera following absorption with either O. volvulus or D. viteae sorbents. Moreover, the IgE antibodies in onchocerciasis patients sera recognized the allergens which were present in the somatic extracts of O. volvulus and D. viteae as revealed by radiolabelled anti-IgE.