Human T cell-B cell hybridomas containing 92 chromosomes were derived by fusing normal stimulated CD-depleted T cells with the EBV-transformed human B cell line 729-HF. These hybridomas coexpressed the T cell surface markers CD3, CD8, and CD2 and the B cell surface antigens CD19, CD20, CD23, DR, and DQ. They weakly and variably expressed surface IgM and TCR. Genomic analysis revealed the presence of rearranged Ig genes as well as beta-T cell receptor genes that could be ascribed to the B and T cell parent, respectively. Analysis of TCR rearrangement suggests that the T-B hybridomas are, in fact, subclones of a single dominant clone. Although the hybrids expressed CD8 and not CD4, following preincubation with PWM, some the of clones induced IgG synthesis from normal B cells while the parent B cell line failed to demonstrate this activity. Stimulation of the hybridomas with PMA down-regulated the T cell lineage-specific antigen display (CD3, CD8, and TCR) and increased IgM production from the hybrids without changing B cell surface antigen display. These hybridomas may be useful to dissect the steps involved in the ultimate commitment of a cell to the B or T cell lineages and will be made available to interested investigators.
Antigens, CD B-Lymphocytes