ANTIBODY-INDEPENDENT ACTIVATION OF ALTERNATIVE COMPLEMENT PATHWAY IN HUMAN-SERUM BY PARASITIC CELLS

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 32  (2) , 245-249
Abstract
The lysis of the monocellular parasite Trypanosoma cyclops by normal human serum (NHS) was complement[C]-dependent and followed activation of the alternative pathway without apparent requirement for conventional antibodies. Lysis of the organisms was inhibited by heat-inactivating NHS at 56.degree. C, preincubation of NHS with cobra venom factor of chelation of divalent cations with EDTA. It took place in human C2-deficient serum and was inhibited by prior heating of NHS at 52.degree. C to destroy the activity of factor B of the alternative pathway. The lytic reaction was Mg- but not Ca-dependent. Repeated low-temperature (0.degree. C) absorption of human hypogammaglobulinemic serum or NHS with the parasite failed to remove or significantly decrease their lytic activities.