Rapid development of a cancer-like antigen in normal tissue in vitro.

Freshly excised human embryonic tissue used as antigen to test lymphocytes from a cancer bearing patient gives a "normal tissue" result of about 10% in the macrophage electrophoresis migration (MEM) test. When, however, it is grown in vitro and then used as an antigenic stimulant to cancer lymphocytes, a "cancerlike" result (about 15%) is produced. These new antigenic determinant(s) akin to those associated with cancer basic protein appear rapidly (within 5.5 hours) in vitro. Cultures of "normal" cells are thus antigenically different from the same cells in context in vivo.