Production of T-T hybrids from T cell clones. Direct comparison between cloned T cells and T hybridoma cells derived from them.

It has been assumed, without direct evidence, that T cell hybridomas and non-transformed T cell clones are both good models of normal Ag-specific T cells. To compare directly the difference in activation of cloned normal T cells and T hybridoma cells with the same TCR, cloned T hybridoma cells were obtained by fusing pre-established, myoglobin-specific, Iad-restricted T cell clones (14.5 and 9.27) with BW5147 cells. T cell clones were pre-activated with IL-2 as well as specific Ag before fusion. Cloned T hybridoma A3.4C6 was derived from Lys 140-specific and I-Ed-restricted clone 14.5. The other cloned T hybridoma, C7R14, was a fusion product of Glu 109-specific and I-Ad-restricted clone 9.27. Both T hybridomas showed the same Ag specificity and Ia restriction as the parental cloned T cells. However, C7R14 showed higher apparent affinity and broader cross-reactivity than 9.27. Clone 14.5, but not hybridoma A3.4C6, appeared to stimulate splenic cells to secrete cytokines inhibiting HT-2A cell proliferation. The most striking difference between the clones and hybridomas was that both clones, but neither of the matched hybridomas, were induced to synthesize IL-1 on stimulation with Ag. Finally, both cloned T cells and T hybridomas killed Ag-pulsed Iad-bearing B lymphoma target cells. This evidence suggests that killing function can be inherited from clones to hybridomas. However, the clones were much more efficient at killing than the hybridomas, and the hybridomas were more efficient at IL-2 production than the clones. Thus, matched pairs of clones and hybridomas differ in their capacity to mediate the two functions or may tend to be selected differently during cloning. Thus, although our results generally support the validity of T cell hybridomas as faithful models of the corresponding T cell clones, a number of subtle and not-so-subtle differences indicate that caution must be used in such an extrapolation.