Expression of members of immunoglobulin gene family in somatic cell hybrids between human B and T cells.

Somatic cell hybrids were obtained between human T and B cells and tested for the expression of differentiated traits of both cell lineages. The T-cell parent SUP-T1 is CD3-, CD4+, CD1+, CD8+, is weakly positive for HLA class I determinants, and has an inversion of chromosome 14 due to a site-specific recombination event between an immunoglobulin heavy-chain variable gene and the joining segment of the T-cell receptor alpha chain. The B-cell parent, the 6-thioguanine- and ouabain-resistant mutant GM1500, is a lymphoblastoid cell line that secretes IgG2, kappa chains, and expresses B1, B532, and HLA class I and II antigens. All hybrids expressed characteristics of B cells (Ig+, B1+, B532+, EBNA+, HLA antigens), whereas only CD4 among the T-cell markers was expressed. The level of T-cell receptor beta-chain transcript was greatly reduced and no RNA of the chimeric T-cell receptor alpha-chain joining segment-immunoglobulin heavy-chain variable region was detected. Southern blot analysis indicated that absence of T-cell differentiation markers in the hybrids was not due to chromosomal loss. Rather, some B-cell-specific factor present in the hybrids may account for the suppression.