Concurrent phase I trials of intravenous interleukin 6 in solid tumor patients: reversible dose-limiting neurological toxicity.

Interleukin 6 (IL-6) has antitumor activity comparable to IL-2 in murine models with less toxicity. Because the biological effects of intermittent and continuous infusions may differ, we conducted two concurrent Phase I trials of daily x5, 1-h, and continuous 120-h i.v. infusions to determine the toxicity, biological effects, and maximum tolerated dose of i.v. IL-6. Cohorts of six patients with advanced cancer received escalating doses (1, 3, 10, 30, 100, and 150 microgram/kg/day) of recombinant human IL-6 on days 1-5 and 8-12 of each 28-day course (1-h trial) or on days 1-5 of each 21-day course (120-h trial). Treatment was administered in regular inpatient wards and in outpatient clinics and was withheld in the event of grade 3 toxicity. Sixty-nine patients (1-h trial, n = 40; 120-h trial, n = 29) were enrolled, including 27 with renal cancer and 16 with melanoma. All were ambulatory, and 40 were asymptomatic. Fever (97%), anemia (78%), fatigue (56%), nausea or vomiting (49%), and elevated serum transaminase levels (42%) were the most frequent toxicities. Transient hypotension developed in 23 patients (33%). There were three deaths during the study due to progressive disease and/or infection. There were no objective responses. Dose-related increases in platelet counts and C-reactive protein levels were detected in most patients. Principal dose-limiting toxicities included atrial fibrillation (1 episode in the 1-h trial and 4 episodes in the 120-h trial) and neurological toxicities (3 episodes in the 1-h trial and 4 episodes in the 120-h trial). The neurological toxicities included confusion, slurred speech, blurred vision, proximal leg weakness, paraparesis, and ataxia. These effects were transient and reversed when IL-6 was discontinued. IL-6 can be given by i.v. infusion at biologically active doses with acceptable toxicity. Dose-limiting toxicities consisted mainly of a spectrum of severe but transient neurological toxicities and occasional episodes of atrial fibrillation. The maximum tolerated doses recommended for use with these i.v. schedules in Phase II trials are 100 microgram/kg/day by daily x5 1-h infusion and 30 microgram/kg/day by 120-h infusion. Phase II trials will be performed to determine the antitumor activity of IL-6 and better define its toxicity. Patients in these and other IL-6 studies should be monitored closely for neurological and cardiac effects.

Phase II trials of high-dose interleukin-2 and lymphokine-activated killer cells in advanced breast carcinoma and carcinoma of the lung, ovary, and pancreas and other tumors.

Treatment with interleukin-2 (IL-2) used alone or in combination with lymphokine-activated killer (LAK) cells is known to be an active therapy for patients with advanced renal cell carcinoma and melanoma. To further explore the activity of IL-2/LAK cell therapy in patients with advanced cancer of various primary sites, the Extramural IL-2/LAK Working Group (ILWG) initiated two phase II trials of high-dose IL-2/LAK therapy: one in patients with advanced breast carcinoma, and one in patients with advanced cancer arising in other sites. Patients with advanced renal cell carcinoma, melanoma, colorectal carcinoma, and lymphoma (Hodgkin's and B-cell non-Hodgkin's) were not eligible for the latter trial, but were treated on other ILWG trials that have been reported previously. Sixty-nine patients received high-dose IL-2 (600,000 IU/kg administered by a 15-min intravenous infusion every 8 h) on days 1-5 and days 11-15. Leukapheresis was performed for collection and ex vivo expansion of LAK cells on days 7-10, and the LAK cells were reinfused on days 11, 12, and 14. The studies were designed to determine whether treatment with IL-2/LAK resulted in at least a 40% response rate, a level of activity that was believed to be sufficient to justify the toxicity and cost of IL-2/LAK therapy. An adequate number of patients with carcinoma of the breast (N = 12), pancreas (N = 8), ovary (N = 7), and lung (non-small cell; N = 6) were accrued to assess response; most of these patients had prior chemotherapy that had failed.(ABSTRACT TRUNCATED AT 250 WORDS)

Phase II studies of recombinant human interleukin-4 in advanced renal cancer and malignant melanoma.

Interleukin (IL-4) is a pluripotent cytokine that stimulates proliferation of activated T-cells and has antineoplastic activity against human renal tumors in animal systems. In phase I trials, IL-4 could be tolerated at doses up to 20 micrograms/kg, with dose-limiting toxicities consisting of fever, fluid retention, nasal congestion, and mucositis. We report the results of two separate Phase II trials of IL-4 in 30 patients with metastatic malignant melanoma and 19 patients with advanced renal cancer. IL-4 was administered intravenously every 8 h for 14 doses in two 5-day courses separated by a 9-day interval. The first 27 patients were treated at a dose of 800 micrograms/m2, but after three of these patients developed cardiac toxicities, the dose was decreased to 600 micrograms/m2. One complete response occurred in a patient with metastatic melanoma (duration > or = 30 months). No responses were seen among the patients with renal cancer. The most frequent side effects were fever, nausea, malaise, nasal congestion, and diarrhea. Reversible hepatic and renal dysfunction were also common. Hypotension was infrequent, but transient weight gain due to fluid retention was common. The major life-threatening toxicities were cardiac and gastrointestinal. Suspected cardiac ischemia was observed in two patients, pericarditis in one, and arrhythmias in two. Three patients had major upper gastrointestinal bleeding without evidence of local tumor. We conclude that IL-4, when given as a single agent on this schedule at maximum tolerated dose, does not possess meaningful activity in renal cancer or melanoma.

Nephrectomy for metastatic renal cell carcinoma: a component of systemic treatment regimens.

New immunotherapeutic and chemotherapeutic regimens have altered the medical approach to metastatic renal cell carcinoma (RCC). Surgery for metastatic RCC needs to be reappraised in the context of these developments. We retrospectively examined the course of 25 patients with metastatic RCC who underwent nephrectomy or resection of renal fossa recurrences as an adjunct to intended systemic therapy. Four patients (16%) had complications and there was no perioperative mortality. Of 23 patients who had surgery first, 17 received subsequent systemic therapy and 2 experienced a response. Two patients underwent nephrectomy after achieving a partial response with systemic therapy. Overall, 3 patients (12%) are alive without detectable disease, 8 (32%) are alive with disease, and 14 (56%) are dead of disease, with a median survival of 23.5 months. Nephrectomy for metastatic renal cell carcinoma may be associated with less morbidity and mortality than previously reported. When initial nephrectomy is performed, most patients go on to receive systemic therapy. Within the context of a systemic treatment regimen, nephrectomy continues to play a role in the management of selected patients with metastatic RCC.

Phase IB clinical trial of anti-CD3 followed by high-dose bolus interleukin-2 in patients with metastatic melanoma and advanced renal cell carcinoma: clinical and immunologic effects.

PURPOSE: To determine the maximum-tolerated dose (MTD) of an anti-CD3 antibody, OKT3, in combination with high-dose interleukin-2 (IL-2), and to determine whether OKT3 can enhance the expansion of CD3+, CD25+ (IL-2 receptor alpha [IL-2R alpha])-expressing T cells in the peripheral blood of patients with advanced melanoma and renal cell carcinoma receiving high-dose IL-2. PATIENTS AND METHODS: We performed a phase IB trial of a murine monoclonal anti-CD3 antibody (OKT3) with high-dose IL-2 in patients with advanced melanoma and renal cell carcinoma. Fifty-four patients were enrolled, with cohorts of 10 or more patients receiving escalating doses of OKT3 at 75, 200, 400, and 600 micrograms/m2 on day 1 followed by IL-2 at an initial dose 0.45 and then 1.33 mg/m2 every 8 hours on days 2 through 6 and 16 through 20 (maximum, 28 doses). An additional cohort of 14 patients received high-dose IL-2 (1.33 mg/m2 per dose) alone. Circulating CD3+, CD25+ cells were monitored before therapy and following the initial week of IL-2. RESULTS: A total of 68 patients were enrolled. The MTD for OKT3 was defined as 400 micrograms/m2 based on a reduction in the number of IL-2 doses that could be administered. Increases in CD3+, CD25+ cells were observed within all cohorts; however, the increase was not OKT3 dose-dependent. On the other hand, we found that 60% (nine of 15) of patients tested at OKT3 dose levels of 200, 400, and 600 micrograms/m2 had increases in serum sCD25 (soluble IL-2R alpha) to more than 100,000 U/mL, while none of 10 patients who received IL-2 alone or with OKT3 at the 75-micrograms dose had increases greater than 60,000 U/mL. Of 29 patients with renal cell carcinoma who received OKT3 with IL-2 (1.33 mg/m2), there were three objective tumor responses (all partial responses). In the 16 patients with melanoma who received OKT3 plus IL-2, there was a single objective response (complete response). CONCLUSION: The doses of OKT3 administered on this schedule failed to enhance significantly the number of circulating CD3+, CD25+ T cells and did not appear to increase the antitumor activity of IL-2 alone, which underscores the need for other approaches to enhance the efficacy of IL-2 therapy.

A randomized phase II trial of continuous infusion interleukin-2 or bolus injection interleukin-2 plus lymphokine-activated killer cells for advanced renal cell carcinoma.

PURPOSE: Since 1985, multiple centers have demonstrated that interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells produce durable anticancer responses in patients with metastatic renal cell carcinoma. High-dose recombinant IL-2 (rIL-2) has been administered by intravenous bolus injection (Rosenberg SA, et al: N Engl J Med 313:1485-1492, 1985) and by continuous intravenous infusion (West WH, et al: N Engl J Med 316:898-905, 1987) combined with lymphokine-activated killer (LAK) cells, with both methods producing responses in patients with advanced renal cell carcinoma. The Extramural IL-2/LAK Working Group has conducted a randomized phase II trial of two intravenous high-dose rIL-2 regimens (bolus three times daily or 24-hour continuous infusion) to determine if either one manifests greater anticancer activity or a more acceptable toxicity profile. PATIENTS AND METHODS: Ninety-four patients with measurable advanced renal cell carcinoma were enrolled on this study: 46 to the bolus injection arm and 48 to the continuous infusion arm. On both arms, patients underwent a priming phase of rIL-2 administration, four daily lymphocytaphereses to harvest mononuclear cells that were placed in 3- to 4-day culture for generation of LAK cells, and an rIL-2/LAK coadministration phase. Patients were then observed monthly for evidence of response to this therapy and were offered up to two additional courses of treatment every 3 months if evidence of response was detected. RESULTS: Twenty percent of patients on the bolus injection arm experienced objective responses (three complete responses and six partial responses); 15% of patients on the continuous infusion arm responded (two complete responses and five partial responses). Complete responses were durable, persisting for 310+ to 700+ days. The incidence of severe life-threatening toxicities typical of high-dose rIL-2 therapy was similar in both arms (eg, patients with hypotension requiring pressors: bolus 71%, continuous 63%; oliguria less than or equal to 200 mL/8 hours: bolus 65%, continuous 71%). More episodes of fever, infection, and serum alkaline phosphatase elevation were associated with the continuous infusion arm, while more thrombocytopenia occurred on the bolus injection arm. Four patients (three bolus injection, one continuous infusion) died of respiratory and circulatory failure while under treatment. No clinical or laboratory parameter accompanying treatment on either arm was, by univariate or multivariate analysis, associated with an increased likelihood of response. CONCLUSIONS: Both methods of high-dose rIL-2/LAK cell administration produce nearly equivalent anticancer activity and toxicity in the treatment of renal cell carcinoma. The ability to predict responding patients based on patient or treatment characteristics is not possible.

Phase II trial of high-dose interleukin-2 and lymphokine-activated killer cells in Hodgkin's disease and non-Hodgkin's lymphoma.

Interleukin-2 (IL-2) plus lymphokine-activated killer (LAK) cell therapy has antineoplastic activity in renal cancer and malignant melanoma. In order to explore the activity of this therapy in Hodgkin's disease and non-Hodgkin's lymphoma, the Extramural IL-2/LAK Working Group (ILWG) treated 27 patients on two protocols using high-dose IL-2 and autologous LAK cells. Two of 12 patients with Hodgkin's disease experienced partial responses lasting 6 and 12 weeks. No patient with non-Hodgkin's lymphoma responded (p = NS). The toxicities of therapy were similar to those reported by the ILWG from trials of IL-2/LAK in solid tumors, consisting of transient hemodynamic, cardiopulmonary, renal and hepatic dysfunction, skin rash, fever, and flu-like symptoms. In view of the low response rate and the brief duration of these responses, we do not recommend the regimens reported here for further investigation in Hodgkin's disease or non-Hodgkin's lymphomas.

Interleukin-2, cisplatin, and 5-fluorouracil for patients with non-small cell lung and head/neck carcinomas.

The feasibility and efficacy of treating patients with locally recurrent or metastatic non-small cell lung cancer (NSCLC) or head/neck cancer with interleukin-2 (IL-2), cisplatin, and 5-fluorouracil (5-FU) was tested. Treatment was given every 28 days and consisted of cisplatin, 100 mg/m2 on days 1 and 8; 5-FU, 1,000 mg/m2 by continuous infusion on days 1-3; and IL-2, 12 million units/m2 by i.v. bolus on days 15-19. Thirty-four patients (22 NSCLC, 12 head/neck cancer) were registered in the study. The median age was 58 years; 59% had Karnofsky performance status of 70-80% and over one-half received prior therapy. All patients were evaluable for toxicity and 29 (18 NSCLC, 11 head/neck cancer) were evaluable for response. Twenty-five patients experienced at least one grade 3 or 4 toxicity, but these toxicities were transient and, in general, well tolerated. The response rate was 37% for NSCLC (0 complete response, 7 partial response) and 55% for head/neck cancer (2 complete response, 4 partial response). Two patients with head/neck cancer responded to treatment after failing prior therapy with cisplatin/5-FU alone. The combination of IL-2, cisplatin, and 5-FU is tolerable and active for treatment of NSCLC and head/neck carcinoma; the combination may not be cross-resistant with other chemotherapy combinations. Further studies of IL-2 combined with cisplatin/5-FU are warranted to determine the most effective dose and schedule.

Pathogenesis of pulmonary edema during interleukin-2 therapy: correlation of chest radiographic and clinical findings in 54 patients.

The pathogenesis of pulmonary edema that occurs during interleukin-2 therapy has often been attributed to an increase in pulmonary capillary permeability. However, renal insufficiency, fluid overload, and hypotension also develop in many patients. These manifestations of systemic toxicity may contribute to the development of pulmonary edema during therapy. Understanding the cause of pulmonary edema during interleukin-2 therapy could directly affect patients' care. Therefore, we reviewed the chest radiographs and clinical course of 54 patients who received high-dose interleukin-2 therapy and lymphokine-activated killer cells for advanced carcinoma. The type, frequency, and course over time of pulmonary abnormalities were recorded and correlated with clinical measures of renal function, fluid status, and blood pressure. Focal or diffuse parenchymal lung opacities were found on radiographs in 43 (80%) of 54 patients. Findings of interstitial pulmonary edema were most common, occurring in 76% of patients. Weight gain, hypotension, and elevation of the serum creatinine level were not associated statistically with interstitial edema. Diffuse air-space disease developed in 20% of patients. Focal consolidation, which was associated with positive central venous catheter cultures (p less than .03), developed in 28% of patients. Pleural effusion occurred in 48% of patients and was associated with all types of parenchymal disease. These data suggest that the frequent development of pulmonary edema during interleukin-2 therapy is not due to renal insufficiency, fluid overload, or hypotension, but is more likely the result of an interleukin-2-related increase in pulmonary capillary permeability.

Gossypol effects on endothelial cells and tumor blood flow.

Isomers (-, +) of the antitumor agent gossypol (G) were studied for their ability to reduce tumor ATP and blood flow in rats bearing subcutaneously implanted pancreatic tumors. A 50% reduction in tumor ATP/Pi within ih of a single injection of -G was associated with a 60% decline in tumor blood flow. To determine if these changes in tumor physiology could be due to a direct drug effect on tumor endothelium, G isomers were compared for their ability to alter protein (125I-BSA) permeability and metabolic (32P) labelling of cultured endothelial cells. Treatments for ih produced no endothelial cell leakage, but 24h exposures to either -G (5 microM) or +G (50 microM) produced complete permeability of the monolayers to 125I-BSA. In contrast, 0.5-I.Oh exposures to -G (4 microM) produced 2 to 3-fold increases in phosphorylated 27 kDa heat-shock protein, hsp-27. Hsp-27 phosphoprotein isoforms were differentially labelled following -G and +G exposures with the phosphorylation profile of -G appearing most similar to that of oxyradical producing agents known to induce hsp-27 and injure endothelial cells. We postulate that the tumor ischemic effects of -G are mediated by endothelial response to oxyradical production in a mechanism similar to that of tissue ischemia-reperfusion injury.

Inhibition of interleukin-2-induced tumor necrosis factor release by dexamethasone: prevention of an acquired neutrophil chemotaxis defect and differential suppression of interleukin-2-associated side effects.

High concentrations of tumor necrosis factor (TNF) alpha have been detected in the plasma of patients undergoing immunotherapy with interleukin 2 (IL-2), suggesting that this cytokine may play a role in the fever and shocklike state induced by the administration of high-dose IL-2. Dexamethasone has been shown to inhibit the synthesis of TNF by monocytes activated in vitro by endotoxin. To determine if dexamethasone can exert a similar suppressive effect on IL-2-induced TNF synthesis in vivo, the concentration of TNF alpha was measured in plasma samples serially obtained (a) from cancer patients participating in a phase I dose escalation clinical trial with high-dose IL-2 administered in conjunction with dexamethasone (IL-2/Dex) and (b) from patients participating in concurrent studies with IL-2 alone. In contrast to the high plasma levels of TNF alpha detected in patients receiving IL-2 alone, TNF levels in most of the IL-2/Dex patients remained below the threshold of detectability of our TNF radioimmunoassay. The concurrent administration of dexamethasone also prevented the IL-2-induced increase in serum levels of C-reactive protein, a hepatic acute phase reactant whose synthesis is regulated by proinflammatory cytokines such as TNF. The steroid-treated patients also failed to develop the neutrophil chemotactic defect characteristic of IL-2 recipients. The concomitant administration of dexamethasone increased the maximum tolerated dose of IL-2 approximately threefold and markedly reduced the hypotension and organ dysfunction ordinarily observed in these patients. These results demonstrate that dexamethasone inhibits the release of TNF into the circulation of patients undergoing immunotherapy with IL-2. They further suggest that the altered spectrum and reduced severity of IL-2 side effects observed in patients receiving dexamethasone may be attributable in part to the suppressive effect of steroids on IL-2-induced TNF synthesis.

Interleukin-2 therapy in patients with metastatic malignant melanoma: a phase II study.

Forty-seven patients with metastatic malignant melanoma were treated with two 5-day cycles of 100,000 U/kg recombinant interleukin-2 (IL-2) intravenously (IV) every 4 hours separated by 1 week. This dose and schedule of IL-2 were identical to those used in a previous combined IL-2 and lymphokine-activated killer (LAK) cell phase II clinical trial of the IL-2/LAK Working Group. Patient eligibility criteria, and clinical management guidelines were similar to those used in the previous trial. Forty-six patients were assessable for response. Objective responses were observed in 10 of 46 patients (two complete responses [CRs], eight partial responses [PRs]) or 22% with responses occurring in lung and liver as well as lymph nodes and subcutaneous sites. The median response duration was 8 months. Toxicity was significant; three patients developed myocardial infarction, and one patient died during therapy. Overall the toxicity and response rate for single-agent IL-2 are similar to that observed with IL-2 administered in combination with LAK cells in the previous trial. These results suggest that single-agent therapy with IL-2 when administered in this schedule has significant antimelanoma activity in humans, and that LAK cells generated from peripheral blood add little to the antimelanoma activity of this dose and schedule of IL-2.

Phase I study of high-dose continuous-infusion recombinant interleukin-2 and autologous lymphokine-activated killer cells in patients with metastatic or unresectable malignant melanoma and renal cell carcinoma.

The current study was undertaken to determine the maximum tolerated dose of recombinant interleukin-2 (rIL-2) that could be administered as a continuous infusion in conjunction with autologous lymphokine-activated killer (LAK) cells. All 55 patients in this study received a priming dose of rIL-2 of 1.0 mg/m2 per day given as a continuous infusion over 4.5 days. Patients later received (days 11-16) one of three doses of rIL-2 per day (1.0, 1.25, or 1.50 mg/m2) in conjunction with LAK cells given on days 11, 12, and 14. Because of unacceptable toxicity occurring early in the LAK cell phase of therapy at the rIL-2 dose level of 1.50 mg/m2, we concluded that the maximum tolerated dose of rIL-2 given as a continuous infusion with LAK cells is 1.25 mg/m2 per day.

Metastatic malignant melanoma treated with combined bolus and continuous infusion interleukin-2 and lymphokine-activated killer cells.

Fifty patients with advanced melanoma received high-dose bolus and continuous infusion interleukin-2 (IL-2) with lymphokine-activated killer (LAK) cells in an attempt to improve the therapeutic index of this active but toxic therapy. Treatment began with up to nine bolus doses of IL-2 administered over 3 days. After 1 day of rest, patients underwent daily leukapheresis for 4 days, and the leukocytes were cultured with IL-2 in vitro to prepare LAK cells. Continuous infusion IL-2 was begun 1 day after the last leukapheresis and continued for up to 148 hours; LAK cells were administered on days 1, 2, and 4 of the infusion. Responding patients were eligible to receive up to two additional cycles of therapy at 3-month intervals. Most patients completed each cycle without dose reduction. One patient had a complete response and six patients had partial responses (14% response rate). The complete responder and three of the partial responders (8%) remain free from disease progression with follow-up of 21 to 24 months. Of these four patients with durable remissions, one had extensive liver and lymph node metastases, one had lymph node, pleural, and parenchymal lung metastases, and two had disease limited to lymph nodes or subcutaneous tissues. Seventeen patients (34%) required pressors for hypotension, three patients (6%) developed hemodynamically significant arrhythmias, and six patients (12%) developed dyspnea at rest, but none required intubation and there were no treatment-related deaths. Unacceptable toxicity developed in two patients during bolus IL-2 administration and therapy was aborted; both returned to baseline status within 4 days of discontinuing IL-2. Fever, oliguria, and elevated creatinine or transaminase levels occurred frequently but were also transient. Despite less frequent severe toxicity with this modified regimen, these results confirm the ability of IL-2 and LAK cell therapy to induce durable remissions in some patients with advanced melanoma.

High-dose recombinant interleukin-2 alone: a regimen with limited activity in the treatment of advanced renal cell carcinoma.

Sixteen patients with metastatic renal cell carcinoma were treated with high-dose bolus recombinant interleukin-2 (rIL-2) alone at a dose and schedule identical to those that produced a 35% response rate among 72 patients in a trial reported by the Surgery Branch, National Cancer Institute (NCI), Bethesda, Md, in which rIL-2 plus lymphokine-activated killer (LAK) cells was used for the treatment of renal cell carcinoma. Patients received two 5-day cycles of 100,000 Cetus U/kg (600,000 IU/kg) of rIL-2 infused intravenously over 15 minutes every 8 hours; each treatment cycle was separated by 1 week. No objective responses were seen. The toxicity of rIL-2 given alone at these high doses was similar to that noted with high-dose rIL-2-LAK cell therapy. The lack of responses seen in this trial also differed from the 21% response rate observed by the NCI Surgery Branch, using rIL-2 alone at an identical schedule and dose in 56 patients with renal cell carcinoma. Only minor differences in such recognized prognostic variables as performance status, tumor burden, and rIL-2 dose intensity were noted between this study and other trials reported by the NCI Surgery Branch and by the IL-2-LAK Working Group. Our analysis indicates that, because of the smaller number of patients in our trial, not enough subjects were included with the ideal characteristics to attain the 21% response rate seen in the NCI study. However, the precise nature of these characteristics remains unclear.

IL-4 inhibits IL-2 receptor expression and IL-2-dependent proliferation of human T cells.

Recent studies have shown that IL-4 can affect lymphocyte responses to IL-2. To evaluate the effects of IL-4 on T cell responses to physiologically relevant stimuli, we studied normal human T cells cultured with a low concentration of anti-CD3 mAb and IL-2 in the presence and absence of added IL-4. The addition of IL-4 to cultures of T cells stimulated with anti-CD3 mAb and IL-2 reduced the proliferative response by 49 to 59%. The inhibitory effect was observed in 3-, 5-, and 7-day cultures. Inhibition was dose-dependent with maximal inhibition at concentrations greater than or equal to 5 to 10 U/ml IL-4. IL-4-mediated inhibition occurred early during the T cell response, inasmuch as addition of IL-4 after stimulation for 24 h did not result in significant inhibition. Phenotypic analyses of cells cultured in the presence of anti-CD3 mAb, IL-2, and IL-4 suggested that the mechanism of regulation by IL-4 involves the inhibition of IL-2R expression. The proportion of both CD4+ and CD8+ cells that expressed IL-2R in response to IL-2 was diminished in the presence of IL-4, although HLA-DR levels were unaffected. Soluble IL-2R was also reduced in supernatants of cultures stimulated with anti-CD3 mAb, IL-2, and IL-4 as compared to cultures stimulated with anti-CD3 mAb and IL-2. These findings indicate that when normal human T cells are stimulated in vitro in a manner that approximates a physiologic interaction with Ag in vivo, rIL-4 provides a potent inhibitory signal to IL-2 responsive cells that is likely mediated by IL-4-induced inhibition of IL-2R expression.

Activated endothelial cells resist lymphokine-activated killer cell-mediated injury. Possible role of induced cytokines in limiting capillary leak during IL-2 therapy.

We previously demonstrated that IL-2 promotes the adhesion of NK cells to endothelial cells (EC) and that EC are readily lysed by lymphokine-activated killer (LAK) cells in vitro, suggesting that cell mediated endothelial injury may contribute to the capillary leak syndrome observed in patients treated with IL-2. In this investigation, we sought to determine the effects of EC activation on the in vitro susceptibility of EC to LAK cell-mediated cytolysis. Despite increased binding of CD16+ lymphocytes to TNF-activated EC monolayers, prior exposure of EC to any of several IL-2-inducible cytokines including TNF-alpha, IL-1 beta, and IFN-gamma not only failed to render the EC more vulnerable to cytolysis but increased their resistance to LAK cells in 111Indium release cytolysis assays. This decrement in susceptibility to cytolysis resulting from prior exposure to cytokines preceded any detectable increase in HLA class I or II Ag expression. In cold target competition experiments with LAK cell effectors and radiolabeled K562 target cells, TNF-primed EC were no more competitive than unstimulated EC, and in assays with unstimulated PBMC effectors, the addition of unlabeled TNF-activated EC actually increased the cytolysis of the radiolabeled tumor cells. The effects of various cytokines and lymphocyte preparations on EC permeability were also evaluated. In these experiments, saphenous vein EC were cultured on porous filter disks, exposed to cytokines or lymphocytes, and the diffusion of 125I-BSA through the filters was then measured. Exposure to IL-2, IFN-gamma, or TNF-alpha did not increase the diffusion of the BSA through the EC-coated filters, whereas LAK cells markedly increased their permeability. Consistent with the results of the cytolysis assays, pretreatment of the EC with TNF, IL-1, or IFN-gamma diminished the LAK cell-induced increase in BSA diffusion. These results suggest that although circulating IL-2-inducible cytokines such as TNF and IFN-gamma may activate EC in vivo and contribute to lymphocyte margination and lymphopenia, they may not be directly responsible for the IL-2-induced capillary leak syndrome and may actually protect EC from LAK cell-mediated injury.