Expression of immunoglobulin-cross-reactive molecules by neoplastic human T cells. I. Surface detection and isolation of molecules reactive with chicken anti-F(ab')2, anti-alpha and anti-mu antibodies.

There is evidence that the T-cell antigen receptor is immunoglobulin-related and that normal human T cells express surface determinants which cross-react with chicken anti-F(ab')2, anti-alpha and anti-mu antibodies. Surface marker study of six neoplastic human T cell lines suggested that F(ab')2- and mu-cross-reactive determinants may be expressed independently of alpha-cross-reactive determinants. F(ab')2-cross-reactive materials--F(ab')2-CRMs--were then isolated from several T-cell lines and analysed by reverse passive haemagglutination and in immunoprecipitation experiments by polyacrylamide disc gel electrophoresis in buffers containing sodium dodecyl sulphate (SDS-PAGE) under reducing conditions. It was shown that MOLT-4- and CCRF-CEM-derived F(ab')2-CRMs differ serologically and that alpha- are indeed expressed independently of F(ab')2- and mu-cross-reactive determinants. The F(ab')2-CRMs were shown to be T cell-derived, to express determinants similar to or identical with F(ab')2-cross-reactive determinants expressed in normal T-cell membranes and to correspond closely to T-cell antigen binding molecules. Evidence was also obtained that the two F(ab')2-CRMs differ from one another in molecular weight. SDS-PAGE under non-reducing conditions of MOLT-4- and CCRF-CEM-derived F(ab')2-CRMs identified major components of mol. wt. 135,000 and mol. wt. 330,000 respectively. Immunoprecipitation of 125I-labelled F(ab')2-CRMs by chicken anti-F(ab')2 followed by SDS-PAGE under reducing conditions identified major components of mol. wt. 80,000 and mol. wt. of 51,000 from CCRF-CEM-derived F(ab')2-CRMs and tentatively identified components of mol. wt. 52,000 and mol. wt. 23,000 from MOLT-4-derived F(ab')2-CRMs.