The induction of functional mononuclear and multinuclear macrophages in murine brugian filariasis: morphological and immunological properties.

This present study describes the ontogeny and morphology of mononuclear and multinuclear macrophages in murine Brugia pahangi infections. Intraperitoneal infection with L 3 resulted in the development of adult worms and the production of microfilariae in many mice; however, all worms were usually removed by 100 days post infection (p.i.). The infection induced predominantly mononuclear and multinuclear macrophage responses in the peritoneal cavity, with maximum numbers of peritoneal cells being achieved by 8-12 weeks p.i. and at this time some 20% of the macrophages were multinucleated. Lymphocyte numbers were also increased during infection. The reactions around the filariae involved macrophages (both single and multinucleated), eosinophils, fibroblasts and the laying down of collagen. Most worms were involved in these cellular reactions by 5-6 weeks p.i., with the multinuclear macrophages generally seen lying close to the parasites. All stages of parasites developed vacuolar internal changes early in their degeneration with calcification being a later change. The destruction and removal of the sheath was not apparently a prerequisite for degeneration of the body of microfilariae. Rosetting techniques showed that 75% of peritoneal cells (macrophages) in infected animals possessed Fc receptors compared with 32% of those in uninfected mice, and for C3 receptors the respective results were 35% and 5%. The multinuclear cells possessed both types of receptors at levels similar to those of mononuclear macrophages. Likewise both cell types were found to readily phagocytose yeast and latex particles, as well as staining positively for non-specific esterases.(ABSTRACT TRUNCATED AT 250 WORDS)