Detection of carcinoembryonic-like antigen on melanoma cells by leucocyte-dependent-antibody assays.

CEA-like antigen has been detected on the surface of some melanoma cells using a rabbit antiserum raised against CEA antigen in 51Cr-release leucocyte-dependent cytotoxic-antibody (LDA) assays. The CEA antigen used for production of the antiserum was shown to be immunologically pure by immunoelectrophoresis procedures and reacted with a reference serum to CEA. The specificity of the CEA antiserum for CEA on the melanoma cells was further shown by removal of reactivity to melanoma cells after absorption on CEA affinity columns. LDA activity to CEA was also shown in a serum taken during pregnancy. No CEA LDA activity was found in several melanoma sera. These findings suggest that CEA may have biological significance in tumour rejection, and that CEA assays may be of value in monitoring disease activity in melanoma patients.