The mouse natural killer T cell-associated antigen recognized by U5A2-13 monoclonal antibody is intercellular adhesion molecule-1

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.

Inhibitory effects of unmethylated CpG oligodeoxynucleotides on MHC class I-deficient and -proficient HPV16-associated tumours

Unmethylated oligodeoxynucleotides containing guanine-cytidine dimers (CpG ODN) have been described as potent inducers of selected antitumour immune responses and the immunotherapeutic efficacy of CpG ODN has been examined either alone or as a vaccine adjuvant. We hypothesized that CpG ODN therapy could be an effective tool for immunotherapy of not only conventional MHC class I(+) tumours but also of those tumours that have lost MHC class I expression during their progression. To address this hypothesis, we employed the animal model resembling MHC class I-proficient and -deficient human papilloma virus (HPV) 16-associated tumours. A cell line transformed with HPV16 E6 and E7 oncogenes, TC-1, as a prototype of MHC class I-positive line, and its MHC class I-deficient sublines TC-1/A9 and TC-1/P3C10 were injected into syngeneic C57BL/6 mice and the growing tumours were subjected to immunotherapy with CpG ODN 1826. The therapy started either 1 day after the challenge with the tumour cells or later, when the tumours had reached a palpable size. In both settings, CpG ODN 1826 significantly reduced the growth of MHC class I-proficient and -deficient tumours. Furthermore, we demonstrated that CpG ODN 1585, whose mechanism of action preferably involves indirect activation of the natural killer cells, induced regression of the MHC class I-deficient tumours TC1/A9 but not of the MHC class I-proficient tumours TC-1. This study infers that synthetic CpG ODN have a potential for the therapy of both MHC class I-proficient and -deficient tumours and thus could be also used against tumours that tend to down-regulate their MHC class I expression.