[Effect of lymphokines produced by human T-T hybridomas on the proliferation of normal and neoplastic B lymphocytes].

Human T-T hybridomas were obtained by fusing T lymphoblasts of the azaguanine-resistant CEM-6 cell line and PHA-activated normal T lymphocytes. After 4 weeks of culture with selective media, proliferating hybrid cells were cloned by limiting dilution. Several clones were obtained and one of them (F2) was shown to secrete a lymphokine with inhibitory activity on the proliferation of an EBV-transformed B cell line, of normal B lymphocytes, as well as of mitogen activated normal T lymphocytes. The proliferation of three other cell lines (MLA-144, CEM-6 and K-562) was not affected. The inhibition of cell proliferation was not due to a cytotoxic effect. The soluble factor from F2 hybridoma was very sensitive to heat-treatment, was not inactivated by target cell adsorption and, finally, it was effective at very low concentrations (70% inhibition at 1:1,000 dilution, v/v). The suppressor activity in the supernatant from F2 hybridoma did not appear to be related to other known lymphokines.