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Purpose: The development of an effective antitumor immune response is compromised in patients with renal cell carcinoma. Despite significant infiltration by T lymphocytes into renal tumors, no detectable induction of gene expression is associated with the generation of an antitumor immune response. Tumor-induced down-regulation of interleukin (IL)-2 expression may contribute to the impaired development of the T cell-mediated antitumor immune response. Within renal tumors, there is no detectable expression of IL-2 or the IL-2 receptor alpha chain, and only low levels of interferon gamma (IFN-gamma) mRNA are detected. Products in the tumor environment may suppress the expression of these genes, thus inhibiting production of type 1 helper T cell cytokines., Methods: Peripheral blood lymphocytes obtained from healthy volunteers were exposed to supernatants from renal cell carcinoma explants, and the immunologic consequences of this were assessed using a variety of molecular assays., Results: Soluble products from renal tumor explants can inhibit the production of IL-2 and IFN-gamma by peripheral blood lymphocytes and can suppress T-cell proliferation. Soluble products from renal cell carcinoma explants appear to block the nuclear translocation of nuclear factor kappa B (NFkappaB) proteins p50 and RelA without affecting cytoplasmic levels of these proteins. In some experiments, a reduction in the nuclear translocation of other transcription factors involved in IL-2 gene expression, including nuclear factor of activated T cells and accessory protein-1, was observed. Gangliosides isolated from tumor supernatants blocked the production of IL-2 and IFN-gamma in response to ionomycin plus phorbol myristate acetate stimulation. These gangliosides also inhibited stimulus-dependent activation and nuclear accumulation of NFkappaB. Coculture experiments demonstrated that renal cell carcinoma lines known to express gangliosides could inhibit the activation of NFkappaB in normal T cells and the Jurkat T-cell line. Supernatants from renal cell carcinoma explants and renal cell carcinoma cell lines can also suppress the proliferation of normal T cells, thus reproducing another defect observed in tumor-infiltrating lymphocytes. Supernatants from renal cell carcinoma tumors also appear to inhibit signaling through the IL-2 receptor. Although tumor supernatants had little effect on IL-2 receptor (alpha, beta or gamma) expression, they did block expression of JAK3, a key kinase involved in signaling through the IL-2 receptor pathway. Moreover, downstream events in IL-2 receptor signaling linked to JAK3 were impaired in T cells treated with tumor supernatants., Conclusion: These findings suggest that soluble products from renal tumors may suppress T-cell responses by blocking both IL-2 production and normal IL-2 receptor signaling.

The expression of three chemoattractant cytokine (chemokine) messenger (m)RNAs in the murine renal cell carcinoma (RENCA) from mice treated with a combination of interferon-alpha (IFN-alpha) and interleukin-2 was examined and related to tumor infiltration by inflammatory leukocytes. Using a semi-quantitative reverse transcriptase polymerase chain reaction assay, mRNAs encoding the KC, JE, and IP-10 genes were all elevated in tumor tissue from mice treated systemically with IFN-alpha/interleukin-2 for 4 days. Similarly, the mRNA for tumor necrosis factor-alpha (TNF-alpha) was also increased in tumors from treated as compared to control animals. The same tumors showed a significant increase in Mac-1+ leukocytes, which correlated well with the increase in chemokine and TNF-alpha gene expression. The renal cell carcinoma tumor itself may be responsible for the expression of chemokine genes in the tumor bed following cytokine therapy. Cultures of freshly explanted RENCA cells expressed significant levels of chemokine mRNAs when stimulated in vitro with IFN alpha, IFN gamma, and/or interleukin-2, demonstrating that this tumor cell has potential for expression of these genes in vivo. In contrast, TNF-alpha expression was not detected in cultured tumor cells. Thus TNF-alpha may be expressed by infiltrating monocytes following exposure to recombinant cytokine therapy.

The combination of IFN-gamma and IL-2 has been demonstrated to induce or promote transcription from selected inflammatory cytokine genes in both monocytes and macrophages. In the present report, we have evaluated the ability of these agents to activate nuclear proteins, in murine peritoneal macrophages, that are capable of specific binding to the kappa B nucleotide consensus sequence (e.g., nuclear factor binding the kappa B consensus sequence (NF kappa B)), which is present in the region 5' of the transcription start site of many cytokine genes. Both IFN-gamma and IL-2 treatments alone caused some activation of NF kappa B, as evidenced by the appearance of a characteristic DNA-protein complex in electrophoretic mobility shift assays; in combination, the two agents cooperated to increase binding activity markedly, to a level equivalent to that seen in macrophages stimulated with LPS, another potent stimulus of macrophage cytokine gene expression. The binding activity was directed toward the kappa B sequence, based upon competition studies with several different oligonucleotide probes containing the kappa B motif in different contexts. The complex formed in cells stimulated with either IFN-gamma/IL-2 or LPS contained two proteins, of approximately 50 kDa and 65 kDa, based upon UV cross-linking experiments with a bromodeoxyuridine-substituted oligonucleotide probe. Although the effects of LPS and IFN-gamma/IL-2 on NF kappa B activity were both transient, response to LPS was detected earlier and declined more rapidly than that seen with IFN-gamma/IL-2 treatment. The cooperative activation of NF kappa B was dose dependent for both IFN-gamma and IL-2. The activation of NF kappa B by IFN-gamma/IL-2 did not depend upon protein synthesis. These results suggest that the induction of cytokine gene expression in macrophages by the combination of IFN-gamma and IL-2 may involve the activation of NF kappa B.

Development of multidrug-resistance (MDR) remains a major cause of failure in the treatment of cancer with chemotherapeutic agents. In our efforts to explore alternative treatment regimens for multidrug-resistant tumors we have examined the sensitivity of MDR tumor cell lines to lymphokine activated killer (LAK) cells. Adriamycin (ADM) resistant B16-BL6 melanoma, L1210 and P388 leukemic cell lines were tested for sensitivity to lysis by LAK cells in vitro. While ADM-resistant B16-BL6 and L1210 sublines were found to exhibit at least 2-fold greater susceptibility to lysis by LAK cells, sensitivity of ADM-resistant P388 cell was similar to that of parental cells. Since ADM-resistant B16-BL6 cells were efficiently lysed by LAK cells in vitro, the efficacy of therapy with LAK cells against the ADM-resistant B16-BL6 subline in vivo was evaluated. Compared to mice bearing parental B16-BL6 tumor cells, the adoptive transfer of LAK cells and rIL2 significantly reduced formation of experimental metastases (P less than 0.009) and extended median survival time (P less than 0.001) of mice bearing ADM-resistant B16-BL6 tumor cells. Results suggest that immunotherapy with LAK cells and rIL2 may be a useful modality in the treatment of cancers with the MDR phenotype.

We have examined the effects of interleukin 2 (IL-2) treatment either alone or in combination with interferon (IFN) gamma or beta on the expression of several activation associated genes (e.g. tumor necrosis factor alpha (TNF alpha), IFN-inducible 10-kDa protein (IP-10] in murine peritoneal macrophages. IL-2 alone did not induce the expression of either gene while IFN gamma or IFN beta had a modest inductive effect on IP-10 but no effect on TNF alpha expression. When either form of IFN was used in combination with IL-2 there was a marked synergistic induction of both mRNAs. IFN gamma and IL-2 were maximally effective when both agents were added simultaneously, and induced mRNA expression declined over a 24-h period in cells pretreated with IFN gamma prior to addition of IL-2. Expression of both genes following combination lymphokine treatment was mediated by increased transcriptional activity. The responses to all three lymphokines were dose dependent; the concentration requirement for IL-2 indicated interaction with an intermediate or low affinity receptor. The expression of both monokine genes was transient and was comparable although not identical to that seen in cells stimulated with lipopolysaccharide. IFN gamma and IL-2 could synergize to stimulate the expression of either TNF alpha or IP-10 mRNA using sequential non-overlapping treatment periods regardless of the order in which the two stimuli were applied to the cells. The effect of either agent alone induced a transient (1-5 h) responsive state with respect to subsequent stimulation with the second agent. Expression of both monokine genes in response to IFN gamma/IL-2 treatment was independent of protein synthesis as cycloheximide did not inhibit the accumulation of specific mRNA. Interestingly, the combination of IL-2 and cycloheximide was as effective as IFN gamma and IL-2 together. In concert, these results indicate that both IFN and IL-2 generate independent intracellular signals which alone are incapable of inductive effect but which are potent activators of inflammatory gene expression when coincidentally expressed.

Studies from our laboratory and others have demonstrated that alpha-interferon (IFN alpha) can regulate natural killer cells and lymphokine-activated killer (LAK) cell activation. In vitro experiments have shown that IFN alpha has differential effects on both natural killer cells and LAK activity when combined with interleukin 2 (IL2); IFN alpha synergized with IL2 to augment natural killer cells activity while it suppressed the IL2-induced LAK response. Here we demonstrated that IFN alpha A/D can also regulate IL2-induced LAK activity in vivo with enhanced or suppressed activity depending on the IFN alpha A/D dose. The enhanced response was observed with the combination when 80,000 units/day of IFN alpha A/D were used and was detectable in the spleen, lung, and peritoneum. When a high dose of IFN alpha A/D was combined with IL2, a moderate reduction in LAK activity was noted in the spleen and peritoneum. In contrast, a high dose IFN alpha A/D augmented IL2-induced LAK activity in the lung even though it reduced the level of cellular infiltration. We have also evaluated the effect that IL2, IFN alpha A/D, and IL2 plus IFN alpha A/D have on the frequency of LAK precursors in the spleen and lung using limiting dilution analysis. Treatment of normal mice with IL2 alone increased the frequency of LAK precursor (LAKp) in the lung. This increase was associated with an infiltration of Thy-1+, asialo-GM1+, Lyt-2- lymphocytes into the lungs. Moreover, treatment with IL2 plus IFN alpha A/D enhanced the frequency of LAKp over that observed with IL2 alone. Treatment with the combination did not change the phenotype of LAKp in the lung from that seen with IL2. The increase in LAKp frequency induced by the combined treatment may not be a direct effect of IFN alpha A/D on precursor cells since IFN alpha A/D alone did not increase the frequency of LAKp in vivo or in vitro when added to limiting dilution analysis cultures. In contrast to what occurred in the lung, a consistent increase in LAKp was not seen in the spleen after treatment with IL2 or with the combination, although LAK activity was observed. These results demonstrated that in addition to inducing lytic activity from LAK effectors in vivo, IL2 treatment increased the number of precursor cells within the lung. Moreover, IFN alpha A/D in combination with IL2 influenced the level of LAKp in situ.

To better understand the modulatory effects of interleukin-2 (IL-2) on lymphocyte proliferation, we examined the clonality of the in vitro T-cell response by Southern blot hybridization. Tumor-infiltrating lymphocytes (TILs) grown in the presence of IL-2 for 15-26 days had detectable T-cell receptor beta-chain gene rearrangements, which indicated oligoclonal enhancement in culture in four of nine TIL samples. In contrast, none of 11 uncultured TIL samples had detectable gene rearrangements. Lack of detection in at least three of the five negative, cultured TIL samples could be explained by increased numbers of natural killer cells. We hypothesize that the oligoclonal expansion noted results from the enhanced response of immune-primed T cells to IL-2.

During previous studies on the regulation of cloned T lymphocyte function, we observed that murine cytotoxic T lymphocyte (CTL) clones progressively lose the ability to lyse appropriate target cells during prolonged (24 to 48 hr) incubation with the tumor promoter phorbol myristic acetate (PMA). We further observed that the cytolytic function of PMA-treated CTL clones can be restored by incubation with secondary MLC supernatant (2 degrees MLC SN), a potent source of cytokines. We now report our observations on the nature of the cytokine(s) responsible for recovery of CTL activity. Like 2 degrees MLC SN, the lectin-induced SN from a cloned helper T cell and the lectin-induced SN from a T cell hybridoma can restore cytolytic activity to cloned CTL treated with PMA. In contrast, supernatants from L929 cells, WEHI-3 cells, and P388D1 cells fail to restore cytolytic activity to similarly treated cloned CTL. These data suggest that IL 2 and/or gamma-IFN, but not CSF-1, CSF-GM, IL 3, or IL 1, can influence expression of cytolysis by cloned CTL. Furthermore, highly purified IL 2 can restore cytolytic activity, even when cytosine arabinoside is present to inhibit clonal expansion. Our studies indicate that cytolysis is a reversible function of cloned CTL, and that cytolysis may not necessarily represent an end-stage feature of CTL maturation. Our studies further show that IL 2 is both necessary and sufficient for resumption of cytolytic function by "deactivated" CTL. As such, these observations suggest that IL 2 can regulate not only T cell proliferation but also the expression of cytolysis by some cytolytic T cell populations.

This study examined the kinetics and mechanisms of depressed spleen cell responses to phytohemagglutinin (PHA) that occur during Leishmania donovani infection of BALB/c mice. In co-culture experiments, neither spleen cells from infected animals nor parasite-infected macrophages suppressed PHA responses of normal spleen cells. In addition, parasite-mediated suppression of PHA-stimulated spleen cell proliferation could not be demonstrated. Mice with 2 wk of infection did manifest an impairment in spleen cell production of interleukin 2 (IL 2) and by 8 wk IL 2 activity in supernatants from these cells was reduced by approximately 95%. This finding was not explained by an alteration in the kinetics of IL 2 production. Furthermore, diminished IL 2 activity in supernatants of PHA-activated spleen cells from infected animals was not caused by suppressive factors in these fluids as shown by their inability to suppress IL 2 stimulation of IL 2-dependent T cells. When spleen cells from mice with 8 wk of infection were cultured with PHA and supplemented with exogenous IL 2, there was an approximately 48% increase in mitogenesis. These data indicate that abnormal PHA-induced spleen cell activation in BALB/c mice with L. donovani infection is associated with impaired production of IL 2. In addition, the observation that supplementation of spleen cells from infected mice with IL 2 resulted in partial reconstitution of the PHA response is consistent with a defect in IL 2 responsiveness.

In this report we provide evidence that the generation of cytotoxic T lymphocytes (CTL) involves a differentiation signal in addition to a proliferative signal, and that the differentiation signal is mediated by a factor distinct from interleukin 2 (IL 2). Generation of CTL from nylon wool-nonadherent splenocytes stimulated by heat-treated thymocytes did not correlate with the addition of IL 2-containing supernatants to this factor-dependent bioassay. IL 2 from two different sources and prepared by different methods (purified IL 2 from the LBRM33 cell line and partially purified IL 2 from the EL4 cell line) was not sufficient to generate a cytotoxic response in the bioassay. The inability of IL 2 to generate a cytotoxic response was not due to the use of heat-treated stimulator cells because similar results were obtained with UV-treated cells. As we previously reported, supernatant fluids containing a differentiation/activation factor did generate CTL from nylon wool-nonadherent splenocytes. Supernatant fluid from co-cultures of activated T cells and M phi as well as from cultures of activated M phi contained this CTL helper factor; however, only the former supernatant contained IL 2 activity. These results suggest a factor distinct from IL 2 is providing a differentiation/activation signal that is necessary for CTL development. Although IL 2 was not effective at generating CTL from nylon wool-nonadherent splenocytes, it was capable in some, but not all, experiments of generating a cytotoxic response from unseparated splenocytes. The ability of IL 2 to induce a cytotoxic response from unseparated splenocytes appeared to correlate with the presence of a weak background response seen when unseparated cells were used as responder cells.

We have examined the interrelationship between Interleukin 2 (IL 2) and Interferon gamma (IFN gamma) for the induction of cytolytic activity from inactivated cloned cytotoxic T lymphocytes (CTL). In previous work we showed that treatment of cloned CTL with phorbol myristate acetate (PMA) inactivated their cytolytic function and that these inactivated cells provided an experimental approach to define the cytokines necessary for the induction of cytolysis. We further showed that IL 2 could provide a sufficient signal to restore cytolytic activity to inactivated cells by a process that was independent of cellular proliferation. Here we report that reactivation of the lytic response by IL 2 did not correlate with IFN production. IL 2 had the ability to restore lytic activity to PMA-treated cells but did not induce IFN gamma production. Similarly, IL 2 augmented the preexisting lytic response of non-PMA-treated cloned cells without stimulating IFN gamma production. However, PMA-treated and untreated cells had the capacity to produce IFN gamma when cultured with mitogen. These results suggest that IL 2 mediated reactivation of the cytolytic response and IFN gamma production by a cloned CTL appear to be regulated independently.

Interleukin-2-stimulated lymphocytes or lymphokine-activated killer cells (LAK) have been shown to have anti-tumor activity which is not present in the fresh untreated peripheral blood lymphocytes. This activity has been evaluated in our laboratory using renal cell carcinoma as a target tumor. Two of 8 patients demonstrated significant lysis of autologous tumor while an additional 3 patients lysed the target cells but to a less significant degree. It is not clear why the LAK phenomenon against autologous tumors occurs in vitro in some patients and not others. By identifying the response of patients in vitro, one might be able to select an appropriate population for meaningful clinical trials.

Interleukin 2, a soluble product of activated T lymphocytes, is of central importance in the development of an appropriate T-cell immune response. Defects in the production of or response to this lymphokine have been described in a variety of immune deficiency and autoimmune states, thus suggesting a role in the pathogenesis of such disorders. To investigate potential abnormalities of interleukin 2 in inflammatory bowel disease, we measured its activity in cultures of intestinal mucosa mononuclear cells derived from Crohn's disease and ulcerative colitis patients. Lamina propria mononuclear cells from inflamed and control tissues were incubated with phorbol myristate acetate, and the amount of the lymphokine in the supernatants was quantitated in a biological assay using cloned, interleukin 2-dependent, cytotoxic mouse T-cell lines. We found that, in culture supernatants of cells from both forms of inflammatory bowel disease, interleukin 2 levels were significantly lower than those detected in cultures containing cells from histologically normal mucosa. Low levels were not correlated to duration, clinical activity, and anatomical location of the disease process or corticosteriod therapy. Deficient activity of this essential growth factor could contribute to abnormal T-cell proliferation and clonal expansion at the gut mucosal level, perhaps inducing a defective immune response leading to a chronic inflammatory reaction in Crohn's disease and ulcerative colitis.