Release Of Soluble Interleukin-2 Receptor Research Articles

Transient increase in mitogen-induced lymphoproliferative responses in patients with testicular cancer after BEP chemotherapy

Objectives. To investigate the impact of polychemotherapy on cellular immunity in patients with testicular cancer. Methods. Lymphocyte subpopulations, lymphoproliferative responses to mitogenic stimulation, and mitogen-induced release of soluble interleukin-2 receptor from peripheral blood mononuclear cells were investigated in 15 patients with testicular germ cell tumors a median of 61 months (range 7 to 73) after polychemotherapy with bleomycin, etoposide, and cisplatin (BEP). Results. The numbers of peripheral blood T cells (CD3+), CD4+ and CD8+ subsets, and lymphoproliferative responses to pokeweed mitogen, phytohemagglutinin, and concanavalin A in patients were comparable to those of healthy control subjects. When two groups of patients were formed according to elapsed time from BEP polychemotherapy and study onset (group A, 12 months and group B, 69 months after termination of BEP), a significant increase in lymphoproliferative response to concanavalin A ( P <0.05) was found in group A 1 year after chemotherapy. Conclusions. BEP chemotherapy administered to patients with testicular cancer does not result in impairment of cellular immunity but rather leads to a significant increase in the capacity of patients’ lymphocytes to respond to mitogenic stimulation up to 1 year after polychemotherapy. Moreover, the increased T-cell activity found after BEP therapy may contribute to the high rate of long-term complete remission.

Direct Inhibition of Human CD8 + Lymphocyte Activation by Cyclosporine A and Rapamune-Sirolimus

Cyclosporin A (CsA) and Rapamune-Sirolimus (RAP) have been shown to inhibit the in vitro activation of heterogeneous lymphocyte populations, but little is known about their direct actions on isolated CD8 + lymphocytes. In this study the direct effects of RAP and CsA on a highly purified population of CD8 + lymphocytes were examined. Human CD8 + lymphocytes were purified to near homogeneity and stimulated with anti-CD3 antibody, OKT3, or allogeneic cells in the presence of exogenous human recombinant interleukin 2 (IL2). The effects of CsA and RAP on cell proliferation, the entry into the S phase of the cell cycle, the surface expression of Tac antigen, and the release of soluble IL2 receptor and soluble CD8 were analyzed. When CsA and RAP were included in the stimulated CD8 + lymphocyte cultures, these responses were inhibited. OKT3-stimulated CD8 + lymphocytes were sensitive to lower concentrations of the immunosuppressants than those previously reported for peripheral blood mononuclear cells. RAP was effective at a lower dose than CsA and when the agents were applied in combination, cell proliferation was synergistically inhibited. These results demonstrate that CsA and RAP can inhibit the activation and proliferation of purified CD8 + lymphocytes in response to OKT3 or alloantigen in the presence of IL2.

Rapamycin inhibits the in vitro release of soluble interleukin-2 receptor by activated peripheral blood mononuclear cells (PBMC) independently of the mode of activation

In the present study we compared the effect of rapamycin to that of CsA on the in vitro responses of lectin (PHA), phorbol-ester (PMA) and Ca 2+ ionophore (ionomycin)-activated peripheral blood mononuclear cells by measuring the release of soluble IL-2R (sIL-2R), high levels of which have been detected in clinical syndromes characterized by an ongoing immune activation. PHA was the stimulant associated with high sIL-2R release, whereas ionomycin-induced sIL-2R release only exceeded the background response and the sensitivity of the ELISA kit. The highest sIL-2R release, however, was obtained when PMA was used in combination with either PHA or ionomycin. Rapamycin inhibited the release of sIL-2R in response to all activators, whereas CsA only abolished the ionomycin-induced sIL-2R release. In parallel experiments rapamycin inhibited cell proliferation in response to all stimulants with the exception of PMA/ionomycin, whereas CsA inhibited all proliferation. Our study clearly shows that for optimal sIL-2R release both Ca 2+ and protein kinase C-triggered signals are required and that rapamycin has a distinct advantage over CsA in inhibiting the release of sIL-2R, which has been shown to be a reliable marker of lymphocyte activation either in vivo or in vitro.

Elevated serum levels of soluble interleukin-2 receptors in lung cancer and the effect of surgery

Activation of T lymphocytes leads to the expression of interleukin-2 receptors (IL-2R) on the cell surface (1) as well as the release of soluble IL-2R (sIL-2R) molecules into the circulation (2). T lymphocytes are the predominant IL-2R bearing cells (3) and hence serum sIL-2R level provides a satisfactory indicator of T-cell activation in vivo. Elevated serum levels of sIL-2R have been reported in patients with small-cell lung cancer (4) (SCLC) and non-SCLC (5). Herein, we report a study designed to find out the sIL-2R concentrations in patients with non-SCLC and their changes following surgical resection.

In vitro metabolic inhibition of the human lymphocyte: influence on the expression of interleukin-2 receptors.

We have investigated the effects of energy depletion in human lymphocytes on the expression of the membrane-bound interleukin-2 receptor (IL-2R) and the release of soluble IL-2R. Concanavalin-A (Con-A) and IL-2-transformed lymphocytes were incubated with sodium fluoride, inhibiting the Embden-Meyerhof pathway, rotenone and 2,4-dinitrophenol (2,4-DNP), which are known to disturb mitochondrial high energy production. Rotenone was found to be the most potent inhibitor, with a half maximal effect at 10 nmol/L. 2,4-DNP and sodium fluoride, although not as potent as rotenone, showed marked inhibitory effects in higher concentrations, with half maximal effects at 50 mumol/L and 5 mmol/L respectively. No difference in the inhibition pattern for membrane-bound IL-2R compared with sIL-2R was observed. It is concluded that intracellular synthesis, transport and subsequent membrane insertion or release of receptors important for immunoregulation require high energy phosphate compounds and are sensitive to disturbances in intracellular energy levels.

Effects of hemodialysis on activation of lymphocytes: analysis by an in vitro dialysis model.

Patients undergoing maintenance hemodialysis have impaired immune responsiveness, which appears to deteriorate progressively with the duration of the replacement treatment. It has been suggested that it is caused by a chronic preactivation state of T cells caused by hemodialysis. Each treatment session has been compared with a recurring "acute-phase" inflammatory reaction. In this study, the acute effects of hemodialysis on the activation state and functional responsiveness of normal peripheral blood mononuclear cells have been evaluated by use of an in vitro dialysis model. The dialysis was carried out with either cuprophan or polysulfone membranes, with or without sodium acetate in the dialysis fluid. It was observed that a single session of in vitro dialysis did not induce production of interleukin-2 (IL-2) and did not alter the expression of IL-2 receptor (IL-2R) on the cytoplasmic membrane and the secretion of soluble IL-2R, whereas it induced transcription of mRNA for IL-2R. The proliferative response of lymphocytes to phytohemagglutinin or IL-2 in vitro also did not change after a single dialysis session. There was only a slight decrease of the release of soluble IL-2 receptor by phytohemagglutinin-stimulated cells after dialysis. Dialysis induced an active synthesis of IL-1 by peripheral blood mononuclear cells, even in the absence of sodium acetate in the dialysate bath, but there was no release of IL-1 to the circulating medium. The results show that a single dialysis encounter can acutely prime the activation of human peripheral blood mononuclear cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired urinary excretion of soluble IL-2 receptors in patients with systemic lupus erythematosus and rheumatoid arthritis.

Several previous studies have demonstrated increased in vivo release of soluble interleukin-2 receptors (sIL-2R) in patients with disorders associated with cellular activation. In this study attempting to understand better the role of sIL-2R released in vivo, we investigated the sIL-2R levels in paired serum and urine samples from 25 patients with systemic lupus erythematosus (SLE), 41 patients with rheumatoid arthritis (RA) and 20 healthy subjects. Using an ELISA for sIL-2R, we detected significantly increased urinary sIL-2R levels in normal individuals (868 +/- 114 units/ml) compared to the corresponding serum samples (209 +/- 25, P < 0.001, mean urine/serum sIL-2R ratio: 4.5 +/- 0.6), which suggests that the clearance of sIL-2R from circulation is largely kidney-dependent. The patients with SLE and RA exhibited significantly increased serum sIL-2R levels compared to normals (682 +/- 115 and 734 +/- 101 units/ml, respectively, P < 0.001) and these levels correlated with disease activity. However, urinary excretion of sIL-2R in these patients (SLE: 620 +/- 154 units/ml; RA: 1084 +/- 148 units/ml) was found to be significantly decreased (mean urine/serum sIL-2R ratio in SLE: 0.9 +/- 0.2; in RA: 1.9 +/- 0.2; P < 0.001) compared to normals, possibly contributing to the accumulation of these soluble receptors in the serum of autoimmune patients after their release from cells. Our findings can be attributed either to the binding of the sIL-2R to serum protein(s) or to distinct structural features of serum sIL-2R in SLE and RA patients, interfering with the urinary excretion of these molecules.

Soluble interleukin 2 receptor release, interleukin 2 production, and interleukin 2 receptor expression in activated T-lymphocytes in vitro

Following activation in vitro, peripheral blood mononuclear cells (PBMC) express cell-associated interleukin-2 receptors (IL2R). The present study was undertaken to define the proportion of T lymphocyte subsets that express the IL2R (CD25 antigen) upon different mitogenic stimulation. Double immunofluorescence staining with different fluorochromes, fluorescein isothiocyanate and phycoethyrin, was applied for identification of IL2R positive cells and individual lymphocyte subset. The exact percentage of individual activated lymphocyte subset bearing IL2R was enumerated by photographic counting. There was paucity of IL2R in freshly isolated, unstimulated peripheral blood, PBMC cultured without mitogen, and cultured B lymphocytes. Following pokeweed mitogen stimulation in vitro, 19% of CD4 (T-helper/inducer) lymphocytes and 14% of CD8 (T-suppressor/cytotoxic) lymphocytes expressed IL2R. Similarly, 25% of CD4 lymphocytes and 19% of CD8 lymphocytes expressed IL2R following phytohemagglutinin stimulation in vitro. Contrary to the reported data of Tac-positive cells in human lymphoid tissues, our study revealed that, upon lectin mitogen stimulation, approximately 55% of IL2R positive PBMC were CD4 lymphocytes, and 45% of them were CD8 lymphocytes. These observations imply the plausible notion that interleukin-2 mediated immune activation of T lymphocytes in PBMC is different from that in local lymphoid organs. It was also demonstrated that the release of soluble IL2R (sIL2R) and IL2 production in supernatant from cultured PBMC varied with different lectin stimulation. A significant correlation was demonstrated between the cellular and soluble IL2R but the production of IL2 from activated mononuclear cells bore no good correlation with either the cellular IL2R expression or the release of sIL2R.

Dynamic Changes in Soluble Interleukin-2 Receptor Levels during Treatment of Graves&amp;rsquo; Disease

The activation of T lymphocyte is accompanied by the release of soluble interleukin-2 receptors (sIL-2R) which can be assessed in biological fluids. A prospective study of the dynamic changes in sIL-2R levels was performed in the serum of 10 patients undergoing a medical treatment for Graves' disease. All patients received carbimazole during the study and, when necessary, L-thyroxine to compensate hypothyroidism. sIL-2R levels were measured before (M0) and after the 1st (M1), 3rd (M3) and 6th month (M6) of treatment. The levels of sIL-2R were high at M0 and M1, and decreased significantly between M1 and M3 (p = 0.03). At M0, the levels of sIL-2R were highly correlated with triiodothyronine (T3) levels (p = 0.0003), early [131I] uptake (p = 0.007) and, to a lesser degree, with anti-thyrotropin receptor antibody levels (p = 0.02). At M6, no correlation was found anymore. We conclude that sIL-2R levels are increased in patients with untreated Graves' disease. They are highly correlated with the markers of Graves' disease activity and decrease during medical treatment.

Age-related changes in release of soluble interleukin-2 receptor by murine lymphocytes

The purpose of this study was to investigate whether the presence of soluble interleukin-2 receptors (sIL-2R) in the supernatants of activated splenocytes correlates with age progression in C57BL/6 mice. In addition, the relationship between IL-2R cell surface expression and release of sIL-2R was examined. The results indicated splenocytes from young (3–4-month-old) mice release higher levels of sIL-2R than those from intermediate (18–19-month-old) or old (24–25-month-old) mice. While there was no statistical difference between sIL-2R levels in intermediate and old mice in this study, the old mice did have a slightly higher release of sIL-2R than the intermediate mice. There was a correlation between IL-2R cell surface expression and the level of sIL-2R in the young and the intermediate age groups. In old mice there was no correlation between these two parameters.

Immune Deficiency in Uremia: Interleukin-2 Production and Responsiveness and Interleukin-2 Receptor Expression and Release

We have studied the role of interleukin-2 (IL-2) and its receptors in the impaired in vitro lymphocyte response characteristic of hemodialysis patients treated by means of cuprophane membranes. The proliferative response of T lymphocytes as well as T-cell-dependent B cell proliferation after stimulation with mitogens was significantly reduced in hemodialysis patients. The in vitro production of IL-2 after such stimulation in parallel cultures was found to be similar in patients and in controls. The expression of IL-2 receptor on the lymphocyte cellular membrane in the hemodialysis group was also similar to controls. The in vitro proliferative response of uremic lymphocytes to exogenous IL-2, however, was significantly depressed suggesting a reduced availability of biologically active IL-2 receptor. The release of soluble IL-2 receptor by lectin-stimulated lymphocytes in culture was also significantly lower in the patient group; yet, hemodialysis patients has a strikingly elevated level of plasma soluble IL-2 receptor, and similar high levels were also found in three other groups of end-stage renal disease patients dialyzed by means of cellulose acetate, polysulfone and polyacrylonitrile membranes, as well as in a group of uremic patients on conservative treatment. In the hemodialysis patient group a significant positive correlation between levels of soluble IL-2 receptor and the duration of hemodialysis was found. Since soluble IL-2 receptor has been reported to down-regulate lymphocyte responses, the elevation in plasma levels of soluble IL-2 receptor in hemodialysis patients may be a pathogenetic factor in the progressive development of impaired immunity associated with end-stage renal disease.

Spontaneous T Cell Proliferation and Release of Soluble Interleukin-2 Receptors in Patients with HTLV-I-Associated Myelopathy

Patients with human T lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM) show increased serum levels of soluble interleukin-2 receptors (sIL-2R), a marker of T cell activation. We found that peripheral blood lymphocytes from HAM patients proliferated spontaneously and released sIL-2R when cultured in vitro. Spontaneous proliferation was observed in T cell populations (both CD4+ cells and CD8+ cells), but not in B cell-rich populations or monocyte-rich populations. There was a significant increase of IL-2 activity in the culture supernatants of peripheral blood mononuclear cells (PBMC) after 2-3 days cultivation. On the other hand, sIL-2R concentrations in the supernatants were much higher after 5 days of cultivation. Such spontaneous T lymphocytic proliferation and release of sIL-2R were also found in non-HAM HTLV-I carriers, but not as intensely as in HAM patients. HTLV-I infection causes T cell activation to release IL-2 and sIL-2R; such T cell responses may play a role in the pathogenesis of HTLV-I-associated myelopathy.

Immune Activation in Measles

Measles is associated with alterations in immune regulation that sometimes lead to secondary infections or autoimmune encephalomyelitis. Simultaneously, an effective measles virus-specific immune response develops. To relate immune activation to measles and its complications, we studied the spontaneous proliferation of blood mononuclear cells and circulating levels of soluble interleukin-2 receptor and CD8 T-cell antigens in 126 patients with complicated or uncomplicated measles at various stages of the disease. Spontaneous proliferation of mononuclear cells, which was present through the first week of the rash, was greater in cells from patients with measles (8787 +/- 1403 cpm) than in those from healthy children (1529 +/- 237 cpm, P less than 0.0001). Levels of soluble interleukin-2 receptor (3385 +/- 195 units per milliliter) and CD8 (4145 +/- 437 units per milliliter) were higher in patients with measles than in those with other infectious diseases (2377 +/- 440, P = 0.003; 2399 +/- 771, P = 0.0374) or in healthy children (865 +/- 138, P less than 0.0001; 1026 +/- 169, P less than 0.0001). Levels of soluble interleukin-2 receptor were elevated before the onset of the rash and remained elevated for several weeks. In contrast, levels of soluble CD8 increased only when the rash appeared, and subsided quickly. Spontaneous proliferation of mononuclear cells and levels of soluble CD8 were similar in patients with uncomplicated disease, pneumonia, or encephalomyelitis, but soluble interleukin-2 receptor levels were lower in patients with encephalomyelitis (2312 +/- 314 vs. 3455 +/- 247 units per milliliter in uncomplicated measles; P = 0.01). In patients with encephalomyelitis, cerebrospinal fluid levels of soluble CD8 (686 +/- 350 units per milliliter), but not interleukin-2 receptor (9 +/- 8.3 units per milliliter), were increased. We conclude that the proliferative phase of the immune response, as measured by the release of soluble interleukin-2 receptor, begins before the rash appears, continues for several weeks in those without complications, but does not occur within the nervous system. In contrast, the effector phase of the immune response, as measured by the release of soluble CD8, coincides with the appearance and disappearance of the rash and occurs within the nervous system during encephalomyelitis.

Release of soluble interleukin-2 receptors (Tac peptide) in vivo during human immune responses to tuberculin

Cutaneous levels of soluble interleukin-2 receptor (Tac peptide) have been measured in tuberculin responses in 13 human volunteers by assaying the fluid present in suction-induced blisters at various times after injection of standard purified protein derivative of tuberculin (PPD). Low levels of Tac peptide were found in blisters without prior injection of PPD and in PPD-negative individuals, and maximal levels of Tac peptide were correlated with increased induration at 48 hr ( r = 0.69, P = 0.04) in PPD-positive subjects. This is the first report of measurement of Tac peptide in vivo in a defined immune response in man, and may offer a new approach to the study of human immune function in vivo.

Immunoregulatory T lymphocytes in man. Soluble antigen-specific suppressor-inducer T lymphocytes are derived from the CD4+CD45R-p80+ subpopulation.

Regulation of the immune response in man is largely dependent on interactions between cells of the cluster designation 4+ (CD4+) helper/inducer sublineage and the CD8+ suppressor/cytotoxic sublineage. When cultured with autologous antigen-primed CD4+ lymphocytes, CD8+ cells differentiate into suppressor T cells (Ts) that specifically inhibit the response of fresh autologous CD4+ cells to the priming antigen only. The current study was undertaken to analyze the roles in this suppressor circuit of subpopulations of the CD4+ sublineage distinguished from one another on the basis of their binding (or lack of binding) to monoclonal antibodies against molecules p80 (Leu8) and CD45R (p220/Leu18/2H4). When examined for the proliferative responses to alloantigenic stimuli, each of the four: CD4+p80+, CD4+p80-, CD4+CD45R+, and CD4+CD45R- populations proliferated vigorously, synthesized interleukin 2 (IL-2) and interferon and released soluble IL-2 receptors. However, the responses to soluble antigens such as Candida and diphtheria toxoid were exhibited by CD4+CD45R-, CD4+p80+, and CD4+p80- cells, but not by CD4+CD45R+ cells. When examined for their ability to induced CD8+ Ts in the Candida-driven suppressor-induction culture system, only CD4+p80+ and CD4+CD45R- cells induced strong suppression. Further, when CD4+CD45R- cells were separated into CD4+CD45R-p80+ and CD4+CD45R-p80- subpopulations, despite the ability of both subpopulations to respond to Candida, only CD4+CD45R-p80+ cells induced autologous CD8+ Ts. Activated CD8+ Ts suppressed not only proliferation but also the release of soluble IL-2 receptors by autologous antigen-activated CD4+ cells. Thus, the antigen-specific suppressor-inducer T cells appear to be derived from the CD4+CD45R-p80+ (Leu3+, Leu8+, 2H4-) subpopulation of the CD4+ sublineage.