A spectrophotometric quantitation of cytotoxic action of antiserum and complement by trypan blue.

A method for the quantitation of cytotoxic action of antiserum and complement is described, measuring the incorporation of trypan blue into Ehrlich ascites tumour cells. The incorporation of the dye into the cells in the presence of antiserum and complement was maximum at ionic strength between 0.10 and 0.15, and decreased with increasing ionic strength higher than 0.15. The permeability barrier of the cell against the dye was stable at pH between 7.2 and 7.4. The cytotoxic reaction required Mg and Ca ion, but was inhibited with concentrations higher than 5 mM Mg and 1 MNCa. The incorporation of the dye in the presence of antiserum and complement was more rapid with increasing concentrations of the dye, and depended on temperature. From these findings we obtained optimal condition for the assay of cytotoxic antiserum.