Complement: Substitution of the Terminal Component in Immune Hemolysis by 1,10-Phenanthroline

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Science  28 Jul 1967:
Vol. 157, Issue 3787, pp. 442-443
DOI: 10.1126/science.157.3787.442


The participation of metal ions in the terminal step of immune cytolysis was investigated with chelating agents. 1,10-Phenanthroline induced lysis of sensitized sheep erythrocytes which had reacted with the first eight components of human complement. Hemolysis caused by 1,10-phenanthroline resembled lysis produced by the ninth component of complement in dependence on cell-bound eighth component and on temperature and in inhibition by 0.09M ethylenediaminetetraacetic acid. Bivalent metal ions reduced the hemolytic capacity of 1,10-phenanthroline, and Fe++ inhibited the activity of the ninth component. Since trivalent iron had no such effects, it is postulated that the hemolytic activity of 1,10-phenanthroline and the ninth component of complement is a function of their affinity for Fe++.