Complement-mediated lysis in vitro of newly excysted tapeworms: Hymenolepis diminuta, Hymenolepis microstoma, Hymenolepis nana and Hymenolepis citelli

Abstract Bogh H. , Christensen J.P.B. and Andreassen J. 1986. Complement-mediated lysis in vitro of newly excysted tapeworms: Hymenolepis diminuta, Hymenolepis microstoma, Hymenolepis nana and Hymenolepis citelii. International Journal for Parasitology 16 : 157–161. Newly excysted worms of Hymenolepis diminuta were lysed in 50% normal serum from all 13 animal species tested, including man. Since H. diminuta was neither lysed in complement inactivated serum—by heat or adding EDTA, LPS or CVF—nor in C5-deficient mouse serum, it is concluded that the lysis was associated with the complement cascade. It is shown that H. diminuta can activate the complement system via both the classical and alternative pathway. Furthermore, it is indicated that the lysis is independent of serum antibodies. Hymenolepis nana and H. citelli were also lysed in all normal sera tested, eight and six respectively, while newly excysted worms of H. microstoma were lysed in normal sera from 10 mammals and birds, but not in sera from its hosts, the mouse, rat and golden hamster. This indicates that the complement system of these three species differs from that of the other species tested in such a way that H. microstoma is able to avoid lysis in these sera.