NEUTROPHIL GRANULE PROTEINS - EVIDENCE FOR THE PARTICIPATION IN THE HOST-REACTION TO SKIN MICROFILARIAE OF ONCHOCERCA-VOLVULUS AFTER DIETHYLCARBAMAZINE ADMINISTRATION

The participation of neutrophil granulocytes in the cellular reaction to skin microfilariae of Onchocerca volvulus was studied by immunohist ochemistry. Skin biopsies were obtained from adult Liberian and Uganda n patients with generalized onchocerciasis after exposure to topically applied diethylcarbamazine (DEC) and from untreated patients. After D EC many damaged microfilariae were observed either in dermal infiltrat es or in epidermal microabscesses consisting both of neutrophils and e osinophils. Infiltrates and microabscesses contained some intact granu locytes and many neutrophils releasing myeloperoxidase, elastase, lact oferrin, defensin, lysozyme, alpha 1-antitrypsin and alpha 1-antichymo trypsin. Eosinophils discharged peroxidase and cationic proteins. Rele ased granule proteins and remnants of disrupted granulocytes were foun d on the surface and in close proximity of damaged microfilariae in de rmal infiltrates and epidermal microabscesses. In larger microabscesse s neutrophils were predominant. These observations show that neutrophi ls and not only eosinophils recruit, accumulate, localize around and r elease their helminthotoxic granule proteins such as myeloperoxidase o nto or closely around skin microfilariae of O. volvulus after topical DEC administration. The association between these processes and the da mage of the microfilariae indicated that neutrophils together with eos inophils attack and damage microfilariae of O. volvulus after DEC trea tment in the skin.