BRUGIA-PAHANGI - DIFFERENTIAL INDUCTION AND REGULATION OF JIRD INFLAMMATORY RESPONSES BY LIFE-CYCLE STAGES

It has been hypothesized that different life-cycle stages of filarial nematodes induce different host responses. This concept was examined i n the Brugia pahangi-jird model of lymphatic filariasis by measuring t he kinetics of inflammatory responses to parasite antigens following i ntraperitoneal inoculation of different life-cycle stages. For this pu rpose, viable female or male worms, L3, L4, or microfilarial stages, w ere used. Dead worms served as controls. Worm and microfilarial burden s, pulmonary granulomatous inflammation (PGRN) to soluble adult worm a ntigen (SAWA)-coated beads, and peritoneal eosinophil and macrophage n umbers were assessed at different days post-inoculation. All jirds ino culated with any of these life-cycle stages developed an early PGRN to SAWA which was later significantly reduced. Only viable worms induced down-regulation of the PGRN response. These results indicate that the hyporesponsive state is induced and maintained by all life-cycle stag es. Also, the degree of granulomatous response was influenced by worm burden, with larger worm burdens inducing lower initial levels of PGRN to SAWA. Peritoneal inflammatory responses differed from the systemic response in that numbers of macrophages increased with time and micro filarial accumulation. No correlation was observed between peritoneal inflammatory responses measured by eosinophil and macrophage numbers a nd PGRN to SAWA. (C) 1997 Academic Press.