Pancreatic beta-cells are more sensitive to several toxins (e.g., streptozotocin, alloxan, cytokines) than the other three endocrine cell types in the islets of Langerhans. Cytokine-induced free radicals in beta-cells may be involved in beta-cell-specific destruction in type 1 diabetes. To investigate if this sensitivity represents an acquired trait during beta-cell maturation, we used two in vitro cultured cell systems: 1) a pluripotent glucagon-positive pre-beta-cell phenotype (NHI-glu) that, after in vivo passage, matures into an insulin-producing beta-cell phenotype (NHI-ins) and 2) a glucagonoma cell-type (AN-glu) that, after stable transfection with pancreatic duodenal homeobox factor-1 (PDX-1), acquires the ability to produce insulin (AN-ins). After exposure to interleukin (IL)-1beta, both of the insulin-producing phenotypes were significantly more susceptible to toxic effects than their glucagon-producing counterparts. Nitric oxide (NO) production was induced in both NHI phenotypes, and inhibition with 0.5 mmol/l N(G)-monomethyl-L-arginine (NMMA) fully protected the cells. In addition, maturation into the NHI-ins phenotype was associated with an acquired dose-dependent sensitivity to the toxic effect of streptozotocin. Our results support the hypothesis that the exquisite sensitivity of beta-cells to IL-1beta and streptozotocin is an acquired trait during beta-cell maturation. These two cell systems will be useful tools for identification of molecular mechanisms involved in beta-cell maturation and sensitivity to toxins in relation to type 1 diabetes.

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Natural killer (NK) cells are believed to contribute to the clinical efficacy of cancer immunotherapy using recombinant interleukin-2 (rIL·2) in humans. In previous trials of high-dose i.v. rIL-2, however, no correlation has been established between circulating NK cells and treatment response. Between January 1989 and October 1990, we treated a total of 47 outpatients with advanced tumors using low-dose s.c. rIL·2 and interferon-α-2 (rIFN-α). Therapy consisted of a 2-day rIL·2 pulse at 18 million IU/m2/ day, followed by 6 weeks of rIL-2 (3.6 × 10⁶-4.8 × 10⁶ IU/m²/day × 5 days/week) and rIFN-α (5 × 10⁶-6 × 10⁶U/m² × 3/week). Before and after therapy, we phenotypically evaluated circulating lymphocytes and correlated them with clinical response. During 6-week therapy, peripheral blood lymphocytes bearing the CD 5 6 (NK-cell-associated) surface antigen were increased significantly (p < 0.005) in treatment responders [complete response (CR) and partial response (PR), n = 10; 3.8-fold] and stable disease (SD) patients (n = 20; 2.1-fold), while patients with progressive disease (PD, n = 17) exhibited no significant expansion of circulating NK cells (p > 0.1). After one 6-week treatment cycle, CR/PR patients had significantly more peripheral NK cells, when compared with patients in SD (1.6-fold) and PD (1.9-fold) (p < 0.04). The overall number of circulating lymphocytes was also increased upon therapy (1.6-fold; p ≤ 0.001), but remained independent of response (p > 0.4). These data demonstrate that s.c. rIL·2 and s.c. rIFN-α produce a significant increase in peripheral blood NK cells; this expansion correlates significantly with treatment response in advanced tumor patients receiving long-term combination immunotherapy at outpatient doses.

We evaluated 28 patients with advanced renal cell carcinoma for the initial expression of P-glycoprotein (MDR1 gene product) employing immunocytochemistry. Tumor specimens were obtained upon primary tumor nephrectomy. In all patients, progression-free survival time following nephrectomy was evaluated and correlated statistically with the staining results. Progression-free survival of patients with no or very few ( < 1%) P-glycoprotein-positive tumor cells (n = 8, median survival 27.0 months) was significantly extended (p < 0.04) as compared to patients with 1% or more P-glycoprotein-positive tumor cells (n = 20, median survival 4,0 months). Correlations with histopathological tumor characteristics were insignificant. These results suggest a potential role for P-glycoprotein as a biologic parameter predictive of tumor progression in renal cell carcinoma patients.

Serum concentrations of Interleukin-6 (IL-6) were determined in renal cell carcinoma patients treated with low-dose subcutaneous human recombinant interleukin-2 (rIL-2). In all patients, administration of rIL-2 resulted in a significant increase in IL-6 serum levels to peak values within 4 to 6 hours as measured by enzyme-linked immunosorbent assays (ELISA). Repetitive administration of rIL-2 induced significantly lower IL-6 serum peaks when compared to the initial administration of rIL-2. Cumulative IL-6 release, as expressed by the area under the concentration curve (AUC), appeared to be independent of rIL-2 dose distribution (10 million IU rIL-2/m2 versus 20 million IU rIL-2/m2), and IL-6 serum peaks showed no direct dose dependency. Prior rIL-2 immunotherapy had no measurable effect on rIL-2 induced IL-6 release, while steroids resulted in a significant suppression of secondary IL-6 did not correlate with response to rIL-2 therapy or survival of rIL-2 treated renal cell carcinoma patients.

We treated 14 patients with progressive metastatic colorectal cancer, using a combination of subcutaneous recombinant human interleukin-2 (4.8 × 10⁶ IU/m² three times daily on days 1 and 22, and twice daily on days 2 and 23, followed by 2.4 × 10⁶ IU/m² twice daily on days 3-5, 8-12, 24-26, and on 5 consecutive days per week, starting day 29), recombinant human interferon-α2a (5.0 × 10⁶ U/m² thrice weekly), and 5-fluorouracil (750 mg/m² i.v. bolus on days 15-19, and at weekly intervals thereafter, with a 1-week off-therapy interval every 4 weeks). Therapy was continued until disease progression occurred. Four (29%) and 8 (57%) evaluable patients achieved partial remission and stable disease, respectively; median response duration was 5.9 months. Toxicity of this regimen was moderate; the most common side effects were thrombocytopenia, leukopenia, nausea/vomiting, anorexia, malaise and fevers in all patients, along with diarrhea (63%) and mucositis (54%). Less than 10% of patients developed WHO grade IV toxicity; no toxic deaths occurred. Efficacy of this combination was not substantially different from alternative 5-fiuorouracil-based regimens.

We report on thirty-four patients with metastatic renal cell carcinoma who were treated with a combination of subcutaneous recombinant interferon-alpha and intravenous vinblastine upon progression after previous antineoplastic therapy. Pretreatment included chemotherapy (n = 3), hormonal therapy (n = 6) and immunotherapy (interleukin-2/interferon-alpha, n = 25). In this study, treatment courses consisted of subcutaneous doses thrice weekly of recombinant interferon-alpha at 6 million U/m2 (20 patients, group 2), respectively. Treatment was given over 8 consecutive weeks. Additionally, in all patients, vinblastine was administered intravenously at a dose of 6 mg/m2 in weeks 2, 5 and 8. Of 14 patients treated in group 1, one had a partial response for 6 months (overall response rate 7.14%; 95% confidence interval, 0.18-33.87%), and four had disease stabilization (median duration, 5.0 months). Of 20 patients treated in group 2, there was one patient who achieved a complete response (response duration, 34+ months); in addition, two patients had a partial response (median response duration, 10.5+ months; overall response rate, 15%; 95% confidence interval 3.21-37.89%), and 13 patients exhibited disease stabilization (median duration 5.9+ months). Response rates showed no significant differences when comparing treatment results in patients in group 1 vs group 2. In contrast, significantly less patients treated in group 2 had progressive disease (p = 0.024), as compared to patients in group 1. This treatment combination was overall well tolerated with low to moderate systemic toxicity. In addition, there were no significant differences in frequency or intensity of therapy-related systemic toxicities when comparing patients in group 1 and group 2, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

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