Spontaneous and interleukin-2-modulated cytokine release by bronchoalveolar cells in pulmonary malignancy.

In a recent phase I study of inhalative, human natural interleukin-2 (hnIL-2) treatment of pulmonary metastases from previously resected solid tumors (mainly renal carcinoma), we have reported that this treatment resulted in an increased accessory function of alveolar macrophages (AM) [1]. Encouraged by these data, we investigated the influence of hnIL-2 inhalation on proinflammatory cytokines spontaneously released by AM. Bronchoalveolar lavage was performed in four groups, each of four patients, before and after 2 weeks of daily inhalation of 0, 200,000, 600,000 and 1,200,000 IU of hnIL-2, respectively. Bronchoalveolar cells were cultured without stimulation to allow spontaneous release over a period of 24 h, into the supernatant. Concentrations of tumor necrosis factor-alpha (TNF-alpha), IL-6, IL-8 and macrophage inflammatory protein-1alpha (MIP-1alpha) were determined by the ELISA technique. Before hnIL-2 inhalation, we measured the following spontaneous cytokine release: TNF-alpha: 1,115.4 +/- 469.1 pg/ml, IL-6: 267.5 +/- 67.7 pg/ml cells, IL-8: 137.8 +/- 40.5 ng/ml, MIP-1alpha: 9.5 +/- 6.8 ng/ml. Inhalation of hnIL-2 did not result in any significant changes in these cytokines. Comparing TNF-alpha release in healthy controls (250.6 +/- 46.7 pg/ml) with that of tumor patients (1,115.4 +/- 469.1 pg/ml), we observed significantly (p < 0.05) elevated TNF-alpha levels in the patient group, which did not change significantly in response to IL-2 inhalation. Our data demonstrate that the activation of AM previously observed after hnIL-2 inhalation is not directly related to a hnIL-2-induced cytokine release by bronchoalveolar cells.

Phase I trial of inhaled natural interleukin 2 for treatment of pulmonary malignancy: toxicity, pharmacokinetics, and biological effects.

Safety, local and systemic immunomodulation, and tumor response to treatment with aerosolized natural interleukin 2 (nIL-2) applied five times a day were studied in a Phase I trial in 16 patients with pulmonary malignancies refractory to conventional therapy. The toxicity of inhaled nIL-2 was different from that observed after systemic administration. Reversible airway irritation causing a nonproductive cough represented the dose-limiting toxicity. Mild to moderate reduction of the vital capacity and forced expiratory volume (FEV1) with minor effects on relative FEV1, peak expiratory flow, airway resistance, and PaO2 was experienced by individual patients. In 14 patients suffering from pulmonary metastases due to renal cell cancer, one durable complete response, one partial response, and one mixed response were observed. Inhalation of nIL-2 aerosol resulted in a dose-dependent expansion of pulmonary immunocompetent cells in bronchoalveolar lavage fluid. Posttreatment bronchoalveolar lavage showed an activated lymphocyte phenotype with increased HLA-DR expression. The only systemic biological effect detectable in peripheral blood was a marked increase of soluble interleukin 2 receptor serum levels. We conclude that treatment with aerosolized nIL-2 is an effective means for site-specific immunomodulation and deserves further investigation for the treatment of malignant and inflammatory lung disease.

Bone marrow-derived T-cell clones obtained from untreated acute myelocytic leukemia exhibit blast directed autologous cytotoxicity.

The eradication of minimal residual blast populations by activation of autologous cytotoxic cells with interleukin 2 (IL-2) is a new promising tool in the treatment of acute myelocytic leukemia (AML). However, the immunological effector cells are not yet clearly defined. The present study was designed to investigate the presence of cytotoxic precursor cells in active AML and to identify phenotypical and functional characteristics of autologous anti-leukemic cytotoxic effector cells. For this purpose, mononuclear cells (MNC) containing at least 70% leukemic blasts were isolated from bone marrow of untreated AML and cultured in the presence of 3000 IU/ml recombinant IL-2 (rIL-2) for 6-8 weeks. Under these conditions, T-cells were selected in the bone marrow cultures and overgrew the leukemic blasts. The resulting T-cell populations were cloned by limiting dilution and the clones obtained were characterized for their phenotypical and functional patterns. Totally, cloning resulted in 68 clones and a few cell lines. The clonality was verified by RT PCR analysis of TCR V beta gene expression. All clones obtained stained positive for CD2, CD3, DR and CD56. The vast majority (68%) of T-cell clones/lines was CD4+, a few clones expressed CD8 (19%) or CD4 and CD8, and four clones were of TCR gamma delta origin. Seven of 15 clones tested, including three CD4+, two CD8+ and two TCR gamma delta(+)-clones were found to be cytotoxic against autologous leukemic blast cells. All except one clone expressed oncolytic activities against allogeneic blasts too. One of the TCR gamma delta(+)-clones demonstrated NK activity by lysis of K562 targets. The majority of the T-cell-clones released IL-2, IL-8, TNF-alpha, GM-CSF but only a few IFN gamma and expressed high levels of mRNA for IL-2, TGF-beta and IL-10. None of the clones was found to produce IL-3, IL-4, IL-7 and TNF-beta. The data provide evidence of the existence of T-cell precursors in untreated AML bone marrow differentiating to cytotoxic cells with activity against autologous and allogeneic AML blast cells.

[Animal experiment, pharmacokinetic and clinical studies of intraperitoneal therapy with interleukin-2 (n Il-2) in patients with ovarian carcinoma]. / Tierexperimentelle, pharmakokinetische und klinische Untersuchungen zur intraperitonealen Therapie mit Interleukin-2 (n IL-2) bei Patientinnen mit Ovarialkarzinom.

OBJECTIVE: In an orthotopic transplantation model using human ovarian cancer xenografts we evaluated antitumor effects of nIL-2 as well as its side effects in a clinical phase I/II study. METHODS: In patients with advanced ovarian cancer nIL-2 was administered i.p. in escalating doses every two days by means of a Tenckhoff-catheter. RESULTS: Considerable stimulation of intraperitoneal immune cells was observed without severe toxic side effect WHO grade III/IV. CONCLUSIONS: Due to pharmacological-pharmacokinetic advantages using the i.p. route nIL-2 was very well tolerated and showed considerable stimulation of local immune cells.

Toxicity of local, continuous and cyclic, high-dose bladder perfusion with recombinant and natural interleukin-2 in advanced cancer of the urinary bladder.

We evaluated the toxicity of high-dose local interleukin-2 (IL-2) in 18 patients not eligible for standard treatment of advanced transitional cell bladder carcinoma. Seven received continuous high-dose local natural IL-2 via pump system in the bladder for up to 420 days. 11 received cyclic high-dose local natural IL-2 or recombinant IL-2 for up to 420 days. Treatment was well tolerated and, considering the low rate of toxicity, could be offered in an outpatient setting. Except for local contrast-media hypersensitivity, no serious side-effects were observed. This study provides a basis for the non-toxic use of local IL-2 in future studies to evaluate effectiveness of the treatment or prophylaxis of patients with superficial bladder cancer in order to prevent recurrences.

In vitro studies of cytokine-mediated interactions between malignant glioma and autologous peripheral blood mononuclear cells.

The humoral interactions between three malignant glioma early-passage cell cultures and in vitro interleukin (IL)-1 alpha- and IL-2-activated autologous peripheral blood mononuclear cells (PBMC's) were investigated, employing standard and modified (separated by permeable membranes) mixed lymphocyte tumor cell (MLTC) cultures. In modified MLTC's, glioma cells clearly inhibit proliferation of PBMC's (up to 60%), whereas lymphokine-activated PBMC's enhance glioma cell growth up to 12-fold, as determined by 3H-thymidine incorporation assays. Glioma cells produce both stimulatory (IL-6) and inhibitory proteins (transforming growth factor-beta) for PBMC's. Lymphokine-activated PBMC's secrete IL-1 alpha, IL-2, IL-4, IL-6, interferon-gamma, and tumor necrosis factor-alpha, which may modulate glioma cell proliferation. None of these cytokines stimulated glioma cells as intensely as modified MLTC systems. These observations indicate that in vitro lymphokine-activated PBMC's, although suppressed by humoral glioma-derived factors, may enhance glioma cell proliferation with soluble factors secreted into the culture medium. The authors conclude that glioma-lymphocyte growth regulatory networks include stimulatory and inhibitory factors from both cell populations, which may modulate tumor progression. These observations may have relevance for adoptive immunotherapy in patients with gliomas.

Biologic activity of low dosage IL-2 treatment in vivo. Molecular assessment of cytokine network interaction.

The sequence of activation of the components of the cytokine network subsequent to in vivo application of different dosages of IL-2 is still poorly understood. Although side effects of IL-2 therapy are dose dependent, the dose-response relationship for induction of potentially beneficial or harmful cytokine genes still remains to be studied. We examined the patterns of cytokine gene expression after treatment of chronic hepatitis B patients with various doses of IL-2 in a phase 1 trial. Total RNAs were isolated from PBMC harvested at various time points after s.c. injection of natural IL-2 ranging from 30,000 to 1,000,000 U. Dose-dependent effects on mRNA expression of IL-2, GM-CSF, IFN-gamma, TNF-alpha, and IL-6 were assessed using Northern blotting and slot blotting techniques. A single application of 30,000 U nIL-2 induced selective and long-lasting expression of IL-2, IFN-gamma, and GM-CSF genes, which was not accompanied by accumulation of TNF-alpha and IL-6 mRNAs. Larger dosages of IL-2 induced activation of monokine genes and were associated with systemic side effects. mRNA levels of the different cytokines related to biologic activity and correlated with expression of specific proteins and cellular parameters: IL-2 mRNA with soluble IL-2R serum levels and induction of lymphopenia, GM-CSF mRNA with induction of neutrophilia, and IL-6 mRNA with c-reactive protein serum concentrations. Taken together these data indicate unexpected immunoregulatory activities of very low and nontoxic dosages of IL-2 in vivo.

Pilot study of natural human interleukin-2 in patients with chronic hepatitis B. Immunomodulatory and antiviral effects.

Ten patients with chronic hepatitis B received increasing doses of nIL-2 (30,000 U, 100,000 U, 300,000 U, 1.0 million U) subcutaneously in a phase I trial. Each dose was applied once per week over 3 weeks. Serum samples were taken before and 2, 12, 24, 48 and 72 h after the first application of each dose level. Serum concentrations of interleukin-1 (IL-1), IL-2, IL-6, interferon-alfa (IFN-alpha), IFN-gamma, tumor necrosis factor-alpha (TNF-alpha) and GM-CSF as well as the cytokine-dependent serum components neopterin, beta-2-microglobulin (B2M), C-reactive protein (CPR), soluble IL-2-receptor (sIL-2R) and 2'-5'-oligoadenylate synthetase (2-5 OA) were assayed using ELISAs and RIAs. None of the samples tested contained measurable cytokine levels other than IL-2. A low and non-toxic dose of 300,000 U nIL-2 was already biologically active with induction of neopterin, B2M and sIL-2R. Dose-dependent changes peaked 24-48 h after application. The same patients were then enrolled in a phase II trial. Treatment in five of the patients was continued twice per week for 3 months with a biologically active dose of 300,000 U nIL-2 subcutaneously. Two of these patients as well as another five patients from the original group were treated with 1.0 million U nIL-2 subcutaneously, twice weekly for 3 months. Neither a biologically active but non-toxic dose of 300,000 U nIL-2, nor a toxic dose of 1.0 million U resulted in permanent clearance of hepatitis B early antigen (HBeAg).(ABSTRACT TRUNCATED AT 250 WORDS)

Culture of normal and leukemic bone marrow in interleukin-2: analysis of cell activation, cell proliferation, and cytokine production.

Transplantation of bone marrow autografts activated by culture in interleukin-2 (IL-2) followed by administration of IL-2 represents a novel approach in an attempt to combine ex vivo purging and post-transplant in vivo immunotherapy, and initial clinical results have suggested its feasibility. To further characterize the mechanism of the in vitro anti-leukemia effect, fresh bone marrow from normal donors and from patients with acute myelogenous leukemia (AML) in remission was cultured for 6 days in the absence or presence of IL-2 (1000 IU/ml). Proliferation of CD3, CD8, CD14, and CD56 cells was determined by direct immunofluorescence using flow cytometry. Predominantly T-lymphocytes (CD3+) and to a lesser extent CD56+ natural killer (NK) cells proliferate in 6-day marrow cultures in IL-2. Fresh bone marrow cells have no measurable NK activity when tested against K562 and Daudi target cell lines in a 4 h chromium-51 release assay, and it requires at least 6 days of culture in IL-2 to develop optimal cytotoxic activity. Cytokines released in the supernatants of these cultures were measured by immuno- and bioassays. Tumour necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma), and IL-6 were found to be produced in significant amounts by marrow mononuclear cells during culture in IL-2. Even without IL-2 present, concentrations of these cytokines were increased in 6-day marrow cultures. In contrast, IL-3, IL-7, granulocyte and granulocyte-macrophage colony-stimulating factors (G-CSF and GM-CSF) were below the level of detection of the immunoassay, a result that could be confirmed for GM-CSF and IL-3 by bioassay. The data suggest that culture of marrow from normal donors as well as from patients with AML obtained in remission can generate anti-leukemia effector mechanisms which are non-crossreactive with chemo- and radiotherapy and may contribute to effective ex vivo purging of residual leukemic cells. The transplantation of such IL-2 'primed' marrow may also contribute to an in vivo graft-versus-leukemia effect.

Detection of nonvolatile macromolecules in breath. A possible diagnostic tool?

The analysis of parameters in bronchoalveolar extracellular lining secretions has come into greater use in the diagnosis of diseases of the lung and respiratory passages. The bronchoalveolar lavage (BAL) method is thus used for sampling alveolar fluids or bronchial secretions. However, this method is invasive and therefore cannot be routinely employed for probe sampling. Based on the hypothesis that aerosol particles excreted in human breath reflect the composition of the bronchoalveolar extracellular lining fluid, experiments were performed to concentrate and analyze these aerosols directly using a noninvasive technique. Human exhaled air was directed through a set of cool traps and the condensate of 200 to 400 exhalations examined for nonvolatile components, such as proteins. In experiments conducted with volunteers, the amount of proteins in the breath condensate of 8 healthy individuals (of a total of 10) amounted to between 4 micrograms and 1.4 mg. The proteins were separated by two-dimensional polyacrylamide gel electrophoresis (PAGE) and compared to saliva samples of the respective volunteers. The results suggest that the proteins detected in breath originate partially from the naso-oropharyngeal tract and partially from lower regions of the airways. In clinical tests, the exhaled air of 13 patients suffering from various diseases of the respiratory tract was sampled and analyzed by immunoassays for inflammation parameters, such as interleukin-1 beta (IL-1 beta), soluble interleukin-2 receptor protein, light chain (sIL-2R), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha). In these tests, up to 370 pg IL-1 beta, 120 pg TNF-alpha, and 2,159 U sIL-2R per ml were measured in the breath condensate.(ABSTRACT TRUNCATED AT 250 WORDS)

Tolerance and cerebrospinal fluid pharmacokinetics of intrathecally administered human natural interleukin-2: a phase I trial.

Recombinant interleukin-2 (rIL-2) is at present widely applied in the immunotherapy of various advanced cancers. As a number of side effects following the administration of rIL-2, either alone or in combination with lymphokine-activated killer (LAK-) cells, have been reported, a preparation of human leukocyte-derived and fully glycosylated interleukin-2 was used in the present study. We have recently demonstrated in cats that this natural IL-2 (nIL-2) is well tolerated and that the distribution and elimination half-lifes following intrathecal (i.th.) application are considerably longer than those after intravenous (i.v.) injection. To determine whether these long half-lifes and the good tolerance of i.th. given nIL-2 are also found in man, four patients with meningeosis neoplastica received repeated injections of human nIL-2 i.th.. Cerebrospinal fluid samples were drawn at different time intervals from either the lateral ventricle or lumbar subarachnoid space. The doses of nIL-2 ranged from 2 x 10(4) to 4 x 10(5) IU per injection. Only minor side effects were noted in one patient. The half-lifes for distribution and elimination of i.th. given nIL-2 ranged between 0.5-1.7 hours and 4.9-14.4 hours respectively. A linear relationship exists between the i.th. dose of nIL-2 and the area under the cerebrospinal fluid activity time profile curve.

Interleukin-2 and blood brain barrier in cats: pharmacokinetics and tolerance following intrathecal and intravenous administration.

Single bolus doses of glycosylated human interleukin-2 (n IL-2) in the range of 2.8 x 10(3) to 2.0 x 10(6) IU/kg were administered to anesthesized cats via the cephalic vein (n = 10) or using suboccipital puncture (n = 8). CSF (cerebrospinal fluid) and blood samples were collected by repeated puncture. The n IL-2 concentration in four cats was determined on the basis of its biologic activity using 3H-thymidine incorporation into human ConA-blasts and by radioimmunoassay. In additional experiments radioactivity was determined in cerebrospinal fluid and serum after intravenous and intrathecal (i.th.) application of 5.8 x 10(3) - 3.2 x 10(3) IU/kg of 14C-acetyl-n IL-2 in regular time intervals. CSF and serum concentration time-profiles show a biexponential decline in the plasma elimination phase with half-lives of 4 min (alpha-phase) and 90 min (beta-phase) after intravenous and 20-120 min (alpha-phase) and 2-16 hours (beta-phase) after intrathecal application. There is a trend towards longer terminal elimination half-lives with increasing doses. Interleukin-2 is able to penetrate the blood brain barrier from the circulation into the cerebrospinal fluid and vice versa. Due to a slow rate of penetration and rapid elimination from blood only traces of n IL-2 (2-8 IU/ml) are detected in CSF after i.v. injection of 2 x 10(6) IU/kg, whereas concentrations between 400 and 1600 IU/ml are maintained in CSF for several hours following i.th. administration of 2-10 x 10(5) IU/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian rhythm of soluble interleukin-2 receptor in healthy individuals.

The cytokine levels of soluble interleukin-2 receptor (sIL-2R), interleukin-6 (IL-6) and tumor-necrosis-factor alpha (TNF-alpha) were studied in 12 healthy volunteers at 11 different times of day. TNF-alpha levels were below the detection limit, and IL-6 levels were at baseline values of the respective assay used. Interindividual variations were found for the plasma levels of sIL-2R (179-524 U/ml). Shedded IL-2 receptors displayed a pronounced circadian phase-dependency (p less than 0.0001) with a peak value at 12:29 h and a trough at 4:14 h when a complex cosine function (period lengths: 24 h plus 12 h) was fitted to the data. These findings may be of importance when using sIL-2R as a diagnostic tool as well as in controlling efficacy of drug treatment.

Activity of liposomal interleukin-2 in vitro.

Preclinical in vitro assessment of highly purified natural human interleukin-2 (IL-2) packed in egg lecithin liposomes was performed in short- and long-term T-cell cloning and propagation systems, and in experiments testing induction of lymphokine-activated killer (LAK) cells. Liposomal IL-2 (lip-IL-2) was essentially as active as free natural or recombinant IL-2 for cloning and culture of both helper and cytotoxic alloreactive T cells. However, lip-IL-2 was found to be markedly inferior to free natural or recombinant IL-2 for the induction of LAK cells from normal donors. Nevertheless, lip-IL-2 was able to maintain LAK cytotoxicity of populations preactivated with free IL-2. These results suggest that lip-IL-2 can interact with activated T cells and LAK cells in the same way as free IL-2, but that it is much less efficient at activating LAK-cell precursors.

Control of pteridine biosynthesis in the natural killer-like cell line YT.

The natural killer-like cell line YT constitutively expresses GTP-cyclohydrolase activity whereas 6-pyruvoyltetrahydropterin synthase and sepiapterin reductase are absent. The product, dihydroneopterin triphosphate, is dephosphorylated and oxidized causing neopterin to accumulate in the cells. The activities of the H4biopterin synthesizing enzymes are not controlled by IFN-gamma or the synergistic action of both IFN-gamma and IL-2 as has been shown for monocytes/macrophages (Huber C. et al. (1984) J. Exp. Med. 160, 310) and CD4+ T cells, respectively (Ziegler I. et al. (1990) J. Biol. Chem. 265, 17026). Sepiapterin reductase specifically is induced by incubation of the cells with sepiapterin, leaving GTP-cyclohydrolase, 6-pyruvoyltetrahydropterin synthase and other enzymes related to pteridine metabolism (dihydropteridine reductase, dihydrofolate reductase) unaffected. The data indicate that H4biopterin synthesis is individually regulated in the diverse cellular components of the immune system.

Treatment of chemically induced autochthonous rat mammary and colorectal carcinomas with interleukin-2.

The antineoplastic efficacy of human interleukin-2 (IL-2) in autochthonous methylnitrosourea-induced mammary carcinoma and in acetoxymethyl-methyl-nitrosamine-induced colorectal carcinoma of Sprague Dawley rats has been investigated. Under the conditions applied, IL-2 was non-toxic. In the mammary carcinoma IL-2 was therapeutically inactive. In the colorectal carcinoma, 1200 U IL-2/day exhibited significant antitumour activity in established tumours as well as in tumours treated "prophylactically" before their manifestation (P less than 0.05). The effect of IL-2 seemed to be more pronounced when given before manifestation of colorectal tumours (T/C = 8.7% vs 17.8% in established tumours). The differential sensitivity of the autochthonous mammary and colorectal carcinoma may be explained by differences in their proliferation rates and differences in volumes at the beginning of IL-2 therapy. IL-2 seems to be preferentially active in small tumours with a low proliferation rate, a feature typical of colon tumours.

Interleukin-6 (IL-6) is an intermediate in IL-1-induced proliferation of leukemic human megakaryoblasts.

We have examined the in vitro effects of recombinant human (rh) interleukin-1 (IL-1) on the growth of purified megakaryoblasts obtained from patients with acute megakaryoblastic leukemia. We demonstrate that both IL-1 alpha and IL-1 beta treatment of these cells led to stimulation of DNA synthesis (as shown by increase of 3H-thymidine incorporation up to 35-fold) and also resulted in colony formation of leukemic megakaryoblasts. However, the stimulatory effect of IL-1 was dependent on endogenous production of IL-6, because addition of neutralizing monoclonal antibody (MoAb) to IL-6 abrogated the stimulatory activity of IL-1. In contrast, neutralizing MoAbs to granulocyte (G)-colony stimulating factor (CSF), granulocyte-macrophage (GM)-CSF, and macrophage (M)-CSF failed to counteract the growth-enhancing effects of IL-1. Leukemic megakaryoblasts accumulated IL-6 mRNA and released IL-6 protein into their culture supernatant when exposed to rh IL-1 but failed to disclose transcripts for G-, GM-, and M-CSF under these conditions. Analysis of IL-6 receptor (IL-6R) transcript levels demonstrated that megakaryoblasts constitutively expressed IL-6R mRNA and that these transcripts are down-regulated to undetectable levels upon exposure to IL-1 and IL-6. Increase of 3H-thymidine incorporation by megakaryoblasts could be duplicated by exogenous IL-6 that could be blocked by neutralizing MoAb to IL-6. In conclusion, our results suggest that leukemic megakaryoblasts could produce and secrete IL-6, and express IL-6R, and that the growth-enhancing effect of IL-1 on these cells is indirect, via production of IL-6 by leukemic cells.

Control of tetrahydrobiopterin synthesis in T lymphocytes by synergistic action of interferon-gamma and interleukin-2.

The control of (6R)-5,6,7,8-tetrahydrobiopterin (H4biopterin) synthesis in primed T cells was analyzed by using the human T cell leukemia virus type I (HTLV-I)-transformed T cell line MT-2. In contrast to the slowly progressing induction of H4biopterin synthesis during activation of resting T cells, it is completed during a 59-h period and is directed by a synergism of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2). Both GTP cyclohydrolase and (6R)-(1',2'-dioxopropyl)-5,6,7,8-tetrahydropterin synthase activities are induced by IFN-gamma. They are further enhanced by combined treatment with IL-2, which per se is ineffective. Furthermore, the combined treatment synchronizes the time periods of both maximum activities, now extending from 33 to 44 h. This period correlates with high cellular H4biopterin levels. It is preceded by a fast and transient period of H4biopterin increase which depends on the synergistic action of both IFN-gamma and IL-2. It coincides with a transient increase in sepiapterin reductase activity. In contrast to MT-2 cells, HTLV-I-transformed HUT 102 cells constitutively secrete IFN-gamma and express IFN-gamma mRNA. The accumulation of H4biopterin is suppressed by anti-IFN-gamma polyclonal antibody and correlates with constitutive expression of all H4 biopterin-synthesizing enzymes.

Lymphokine release, suppressor cell generation, cell surface markers, and cytotoxic activity in cancer patients receiving natural interleukin-2.

We monitored patients treated for 5 days with continuous infusion of increasing doses (3 to 6 x 10(6) U/d) of natural interleukin-2 (IL-2). CD16+, CD25+, and CD56+ cells increased after treatment. Plasma tumor necrosis factor-alpha (TNF-alpha) levels, but not interferon-gamma (IFN-gamma) levels, increased during IL-2 treatment, but spontaneous and IL-2-stimulated TNF-alpha secretion in vitro remained abnormally low. However, mitogen-stimulated TNF-alpha release was normal. Mitogen-stimulated, but not IL-2-stimulated, IFN-gamma release was strongly depressed. Low spontaneous and IL-2-stimulated cytotoxicity on K562 or Daudi increased after treatment. Low suppressor cell generation also normalized after treatment. This appears to be the first reported study of immunologic monitoring of cancer patients treated with natural rather than recombinant IL-2.

Modulation of interleukin 2 high-affinity binding by lymphocyte-derived tetrahydrobiopterin: pterins as potential participants in the control of interleukin 2 receptor assembly.

In this report, we have examined whether (6R)-tetrahydrobiopterin (H4biopterin) modulates the binding of interleukin 2 to high-affinity sites of the cloned mouse cytotoxic T-lymphocyte clone CTLL-2. Scatchard plot analysis of the equilibrium binding data reveals increased affinity when the cells are exposed simultaneously to interleukin 2 and to the pterin. The Kd values are statistically significantly reduced from 1.4 x 10(-11) M to 0.78 x 10(-11) M interleukin 2. The dissociation kinetics of the ligand were followed at 4 degrees C after equilibrium binding under high-affinity conditions (1.2 x 10(-10) M interleukin 2). In the presence of H4 biopterin, the dissociation rate constant (k-1) decreases from 6.2 x 10(-3) min-1 to 3.0 x 10(-3) min-1 and the half-time for dissociation increases from 106.8 min to 218.0 min. As a third approach interleukin 2 was bound to the surface of cells under high-affinity conditions by incubation in the cold and the internalization kinetics upon warming were determined. Sigmoidal-shaped kinetics of endocytosis in control cells indicate that the internalization rates increase only gradually. The presence of H4 biopterin causes an apparent immediate transition from higher-order kinetics to a linear response so that maximum internalization rates are reached immediately upon warming. The data show that lymphocyte-derived H4 biopterin in vitro at concentrations ranging from 2-8 x 10(-7) M modulates interleukin 2 high-affinity binding and that H4 biopterin potentially participates in the control of interleukin 2 receptor assembly.