Comparative studies of clinical groups of patients in an onchocerciasis endemic area for evidence of immune-mediated protection.

Four clinical groups of persons from an area endemic for onchocerciasis were compared using certain immunological parameters. The groups were: generalised onchocerciasis, patients with restricted distribution of onchocercal skin lesions, microfilaredermia patients with no clinical manifestations, and a group which clinically, had successfully resisted the infection. Specific serum antibodies to O. volvulus antigens were found in all groups. The IgG specific antibodies were highest in patients with generalised onchocerciasis and lowest in the group who had apparently contained the infection. The sera of persons from the latter group mediated leukocyte adherence to and immobilised microfilariae of O. volvulus. Using the Western blot technique, there were no onchocercal protein antigens that reacted exclusively with sera from the "protected group". However, the staining of the reaction bands was most intense when sera from this patient group reacted with low molecular weight specific onchocercal antigens (M. W. 10-57 KD).