Interferon-gamma production by T lymphocytes from renal cell carcinoma patients: evidence of impaired secretion in response to interleukin-12.

Interleukin-12 (IL-12) is a heterodimeric cytokine that enhances the cytolytic activity, proliferation, and interferon-gamma (IFN-gamma) production by T lymphocytes and natural killer cells, and has significant antitumor activity in a variety of murine tumor models. The induction of interferon (IFN)-gamma by IL-12 in tumor-bearing mice plays an important role in its antitumor activity. We therefore examined the effects of IL-12 on IFN-gamma production by T cells derived from patients with renal cell carcinoma (RCC), including freshly isolated tumor infiltrating lymphocytes (T-TIL), matched peripheral blood T cells (T-PBL), and RCC-specific TIL lines. IL-12 alone induced IFN-gamma secretion by T cells from normal individuals and appeared to act synergistically with either IL-2 or anti-CD3 antibody. In contrast, it failed to stimulate significant IFN-gamma secretion by T-PBL and T-TIL from RCC patients. This unresponsive state in T-PBL appeared selective because IFN-gamma was produced when cells were stimulated with either phytohemagglutinin or anti-CD3 antibody. Moreover, costimulation through the T-cell receptor (TCR)/CD3 complex or with IL-2 made T-PBL from RCC patients responsive to IL-12, possibly secondary to the upregulation of IL-12R (beta chain). A selective loss of IL-12-dependent production of IFN-gamma was also consistently observed in two of three established RCC-specific TIL lines. Although these cell lines did not respond to any concentration of IL-12, they did produce IFN-gamma after ligation of the TCR/CD3 or stimulation with IL-2, IL-12 also acted either syngeristically or additively with IL-2, anti-CD3 antibody, or autologous tumor cells to induce IFN-gamma production. The observed decreases in IFN-gamma production in response to IL-12 may have a negative effect on the development of T-cell immunity. The clinical importance of these findings during in vivo administration of IL-12 remains to be determined.

Responses to T cell receptor/CD3 and interleukin-2 receptor stimulation are altered in T cells from B cell non-Hodgkin's lymphomas.

T cells infiltrating (T-TIL) B cell non-Hodgkin's lymphomas (NHL) are thought to represent a local host response to the tumor. However, tumor progression in the presence of this T cell infiltrate suggests that the T-TIL may be functionally impaired. To address this issue we determined whether response to stimulation of T-TIL from 25 patients with NHL through the T cell receptor (TCR/CD3) and the interleukin-2 (IL-2) receptor (IL-2R) was intact, since activation of these receptors is important for proliferation and cytokine production. Our results demonstrate defects in response to stimulation via TCR/CD3 and the IL-2R in T-TIL cells from patients with NHL that were not observed with T cells from the peripheral blood. T-TIL showed minimal proliferation to anti-CD3 and only modest proliferation to IL-2 alone or when combined with anti-CD3. Moreover, cytokine production in T-TIL was impaired since stimulation through the TCR/CD3 complex did not induce mRNA for interferon gamma (IFN gamma), IL-2, IL-4 or IL-10. The functional unresponsiveness of these cells may be linked to altered signalling through the TCR/CD3 since an abnormal tyrosine phosphorylation pattern was detected in T-TIL after stimulation with anti-CD3.