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.