STUDIES ON IMMUNE CELLULAR INJURY I. CY~oToxlc EFFrCTS OF ANTIBODY AND COMPLEMENT*

The requirement for a group of normal serum factors, collectively designated as complement, for injury or destruction of cells sensitized with antibody has been recognized for more than 70 years (1). The participation of complement in immune destruction of erythrocytes (immune hemolysis) has been most intensively studied, primarily because of technical feasibility. Considerable attention has also been given to the destruction of Gram-negative bacteria by antibody and complement (immune bacteriolysis). Although some evidence is available that normal serum factors resembling complement also participate with antibody in the killing of mammalian cells other than erythrocytes (immune cytotoxicity) (2-13), this activity of complement has been least dearly defined, Investigation of the phenomenon of immune cytotoxicity is of fundamental biological interest from the standpoints of general mechanisms of cellular injury and of specific mechanisms of tissue damage in hypersensitivity states. Although an ultimate aim of such investigation is elucidation of mechanisms of immune injury of human cells in ~ivo, it appeared desirable initially to establish in vitro a model system in which factor requirements and reaction sequences could be studied with greater facility. The model system consisted of freshly isolated normal human amnion cells, rabbit anti-human amnion antibody and normal human serum. The amnion cell was selected because of the desire to establish the model with normal fixed-tissue cells of human origin, the ready availability of sterile human placentas and the relative ease with which suspensions of amnion cells could