Killing of Schistosomula of Schistosoma mansoni by Normal Human Monocytes

Abstract

All mammalian species exhibit some degree of innate resistance to infection with the helminth Schistosoma mansoni. This is manifest experimentally by the discrepancy between the number of infecting cercariae and the resulting mature worm load (1). Even in the most susceptible species, such as the hamster and mouse, no more than 40 to 60% of infecting organisms develop into adult worms (2). In vitro systems have been used to elucidate potential mechanisms of schistosomula killing (3–8). However, the recognized mechanisms all are predicated upon prior schistosomiasis with the development of specific antibodies (3, 4), the availability of eosinophils (5–7), or activation of macrophages (8). The current studies were designed to evaluate possible contributions of circulatory leukocytes to naturally occurring resistance to schistosomiasis. They show that cells derived from circulatory human monocytes can kill schistosomula independent of specific antibody and complement (C).Materials and Methods. Cell preparations.