Immunohistological studies on neoplasms of female and maleOnchocerca volvulus: filarial origin and absence ofWolbachiafrom tumor cells

Abstract

SUMMARYUp to 5% of untreated femaleOnchocerca volvulusfilariae develop potentially fatal pleomorphic neoplasms, whose incidence is increased following ivermectin treatment. We studied the occurrence of 8 filarial proteins and ofWolbachiaendobacteria in the tumor cells. Onchocercomas from patients, untreated and treated with antibiotics and anthelminthics, were examined by immunohistology. Neoplasms were diagnosed in 112 of 3587 female and in 2 of 1570 maleO. volvulus. The following proteins and other compounds ofO. volvuluswere expressed in the cells of the neoplasms: glutathione S-transferase 1, lysosomal aspartic protease, cAMP-dependent protein kinase, alpha-enolase, aspartate aminotransferase, ankyrin E1, tropomyosin, heat shock protein 60, transforming growth factor-beta, and prostaglandin E2. These findings prove the filarial origin of the neoplasms and confirm the pleomorphism of the tumor cells. Signs indicating malignancy of the neoplasms are described.Wolbachiawere observed in the hypodermis, oocytes, and embryos of tumor-harbouring filariae using antibodies againstWolbachiasurface protein,WolbachiaHtrA-type serine protease, andWolbachiaaspartate aminotransferase. In contrast,Wolbachiawere not found in the cells of the neoplasms. Further, neoplasm-containing worms were not observed after more than 10 months after the start of sufficient treatment with doxycycline or doxycycline plus ivermectin.