A sensitive assay for the detection cytotoxic antibodies to mammalian cell surface antigens.

A microcytotoxicity assay for the detection of complement-dependent serum toxicity against adherent cells has been modified to include post-labeling of the target cells with [3H]leucine or [3H]thymidine. The adaptation represents a significant improvement over the visual counting of residual cells. The technique is more objective and less tedious than the original procedure, while retaining the features of economy of cells and sera, reproducibility, and sensitivity. Examples are given which demonstrate the suitability of the modified assay for the analysis of human and mouse tumor antigens using autologous, allogeneic, and syngeneic sera.