MAST-CELL DISTRIBUTION IN NODULES OF ONCHOCERCA-VOLVULUS FROM UNTREATED PATIENTS WITH GENERALIZED ONCHOCERCIASIS

Onchocercomata with a defined worm population were analysed to elucida te the distribution of mast cells. Nodules with live females were clas sified according to the presence or absence of microfilariae. Immunohi stochemical staining was performed using antibodies specific for mast cells or IgE. Mast cells appeared singly or in diffuse accumulations p erivascularly and in inflammatory infiltrates between adult Onchocerca volvulus and in the capsular area. No mast cells were detected in cys tic parts. Only few, scattered mast cells were found in the fibrous zo ne around the adult worm. They were increased with stronger infiltrati on and hence, related to the inflammatory cells. Mast cells were never localized directly at adult worms or microfilariae. A correlation of the mast cell distribution to the occurrence of eosinophils was observ ed regarding higher numbers of mast cells and eosinophils in nodules w ith microfilariae-producing females. Nodules with single males reveale d higher numbers of mast cells than nodules with non-producing females , although both contained very few eosinophils. Onchocercomata with de ad worms contained significantly more mast cells than those with live filariae. In conclusion, the localization and frequency of mast cells is contingent on the vitality and productivity of the worms and theref ore, indirectly and directly on the release of O. volvulus antigens.