Characterization of NKT-cell hybridomas expressing invariant T-cell antigen receptors.

Two natural killer T (NKT)-cell hybridomas were established by fusing sorted NKT cells with BW1100 thymoma cells. The first hybridoma line, 1B6, was CD4(+)8(-), whereas the second one, 2E10, was CD4(low)8(-). Initial characterizations revealed that both cell lines expressed an invariant T cell antigen receptor, which could be readily detected with alpha-galactosylceramide-loaded CD1d : Ig fusion protein (alpha-GalCer/CD1d). Sequence analyses of the alpha and beta chains of the T cell receptor V genes revealed that 1B6 and 2E10 cells expressed V alpha 14J alpha 18/V beta 8.2D beta 2J beta 2.7 and V alpha 14J alpha 18/V beta 8.1D beta 1J beta 1.1, respectively. When these hybridoma cells were stimulated with immobilized anti-CD3 monoclonal antibodies, alpha-GalCer/CD1d, or alpha-GalCer in the presence of antigen-presenting cells, they produced IL-4 and IFN-gamma. The expression levels of CD69, CD154, and CD178 were concomitantly up-regulated on both hybridomas upon stimulation. Because it is difficult to isolate a sufficient number of NKT cells, these hybridomas should provide useful platforms to study a variety of functions of NKT cells.