LYMPH-NODES OF ONCHOCERCIASIS PATIENTS AFTER TREATMENT WITH IVERMECTIN - REACTION OF EOSINOPHIL GRANULOCYTES AND THEIR CATIONIC GRANULE PROTEINS

Lymph node and skin biopsies from Liberian patients with generalized a nd localized (sowda) onchocerciasis were studied 12-68 hours after ora l administration of ivermectin at a single dose of 150 mu g/kg body we ight. Electron microscopic examination and immunohistochemical stainin g with antibodies against two different forms of eosinophil cationic p rotein (ECP EG1, ECP EG2), eosinophil peroxidase (EPO) and cationic le ukocyte antigen (CLA) were performed. Following their disappearance ho m the skin, a large number of microfilariae was found in the regional lymph nodes. The lymph nodes from treated patients had over ten times more eosinophils compared to those from untreated persons with a peak of eosinophil density at 40-48 hours after treatment. Degenerating mic rofilariae in the lymph nodes were encircled by eosinophils, which sho wed positive immunostaining for ECP, EPO or CLA. Intra- and extracellu lar eosinophil granules revealed a great variation in their condition. In some specific granules a variety of structural alterations in the crystalloid cores occurred while in others different stages of deficie ncy in the matrix electron density were observed. The frequent necrosi s of eosinophils in the immediate vicinity and at some distance from t he microfilariae, with subsequent release of granules and the depositi on of toxic cationic granule proteins onto the microfilarial cuticle d uring the eosinophil-parasite adherence reaction, demonstrated the fun ction of these proteins in the ivermectin-reinforced killing of microf ilariae in lymph nodes.