Humoral-mediated suppression of interleukin 2-dependent target cell proliferation in acquired immune deficiency syndrome (AIDS): interference with normal IL-2 receptor expression.

Sera from patients with acquired immune deficiency syndrome (AIDS) were analysed for effects on normal lymphocyte interleukin 2 (IL-2) production, IL-2 receptor (IL-2R) expression and levels of IL-2 dependent T cell proliferation. The presence of AIDS serum appeared to reduce significantly IL-2 production by cultures of mitogen-activated normal human peripheral blood mononuclear cells (PBMC). However, dilution analyses of the culture supernatants indicated that the primary inhibitory effect occurred at the level of the IL-2 responsive target cell. Furthermore, eight of nine AIDS sera, but none of the normal human sera (NHS) tested, suppressed the capacity of IL-2-dependent CTL-20 cells to proliferate in response to human IL-2. Fractionation of AIDS sera by gel filtration on Sephacryl S-200 revealed that inhibitory activity coeluted with the immunoglobulin fraction. Pretreatment of human IL-2R+ lymphoblasts with AIDS serum did not interfere with the binding of monoclonal antibody (anti-Tac) specific for the human IL-2R; however, significant reductions in the levels of phytohaemagglutinin-induced IL-2R expression were observed when normal human PBMC were cultured in the presence of AIDS serum. These findings indicate that the inhibitor present in many AIDS sera does not suppress lymphocyte proliferation by interfering directly with the IL-2 receptor, and suggest that inhibition occurs at a later stage of the cell cycle. One of the primary consequences of the activity of this serum inhibitory factor is a decline in the levels of lymphocytic IL-2R expression.     

Plasma and tissue interleukin-2 receptor levels in inflammatory bowel disease.

Plasma and tissue interleukin-2 receptor (IL-2R) levels were determined in patients with active ulcerative colitis and Crohn's disease. Compared with healthy controls (median 440 U/ml; range 240-900), significantly higher levels of plasma IL-2R were present in patients with active ulcerative colitis (median 1180 U/ml; range 580-7150; P less than 0.002) and Crohn's disease (median 1340 U/ml; range 480-9000; P less than 0.002). Compared with other laboratory parameters, plasma IL-2R levels were related most closely to clinical score of disease activity in Crohn's disease. Plasma IL-2R levels also reflected the clinical course and may provide a more accurate assessment of disease activity in Crohn's disease. In plasma of patients undergoing intestinal resection of active inflammatory bowel disease, raised levels of IL-2R were present in samples from mesenteric vein (draining inflamed intestine) compared with those from peripheral vein. In tissue homogenates of colonic biopsies, significantly higher levels of IL-2R were present in specimens from colons with active ulcerative colitis compared with healthy controls (median 230.2, range 20.7-581.5 versus 77.9, range 34.2-291.3; P less than 0.02).     

Alveolar macrophages from humans and rodents selectively inhibit T-cell proliferation but permit T-cell activation and cytokine secretion.

Alveolar macrophages (AM) are thought to play a key role in the regulation of immune responses within the lung. While it is well established that AM inhibit T-cell proliferation in vitro, it is unclear whether other aspects of the T-cell activation process are also inhibited. The present study demonstrates that AM from rat, mouse and human differ markedly in the potency with which they inhibit mitogen-induced T-cell proliferation, although in humans the degree of inhibition approaches that observed in the animal systems, if antigen (as opposed to mitogen) is employed as the T-cell activating agent. Rodent and human AM also differ in the mechanisms employed to achieve this inhibition; rodent AM appear to utilize reactive nitrogen intermediates, while this does not appear to be the case for human AM. Despite these differences, T cells stimulated in the presence of AM display a similar phenotype in all species examined, i.e. CD3 down-modulation, up-regulation of interleukin-2 receptor (IL-2R) expression and IL-2 production, but inability to respond to IL-2. Thus, AM appear to allow T-cell activation and expression of T-cell effector function, while selectively inhibiting T-cell proliferation.     

Soluble interleukin-2 receptor, interleukin-2 and interleukin-4 in sera and supernatants from patients with progressive systemic sclerosis.

We studied the sera of patients with progressive systemic sclerosis (PSS) for elevated levels of soluble interleukin-2 receptor (sIL-2R), interleukin-2 (IL-2) and interleukin-4 (IL-4). We also measured IL-2, IL-4 and B cell growth factor (BCGF) activity in supernatants of peripheral blood mononuclear cells from the same patients. The finding of elevated serum sIL-2R and IL-2, and the increased levels of IL-2, IL-4 and BCGF activity in culture supernatants indicates that T lymphocyte hyperactivity likely play a major role in PSS. The failure to detect under our experimental conditions a direct proliferative effect of recombinant IL-2 on enriched normal B cells might suggest that IL-4 is the cytokine mainly responsible of the BCGF activity recovered in PSS supernatants.     

Modification of some lymphocyte functions in vitro by opioid receptor agonists and antagonist in chronic uremic patients and healthy subjects.

In ten chronic uremic patients on regular hemodialysis treatment in vitro experiments revealed that stimulation of opioid receptors with morphine did not significantly change the mitogen-induced proliferative response of peripheral blood lymphocytes and interleukin-2 (IL-2) receptor expression on PHA-stimulated lymphocytes, while it appreciably decreased surface transferrin (Trf) receptor expression on PHA-stimulated lymphocytes. However, metenkephalin inhibited mitogen-induced proliferation and surface Trf receptor expression on uremic lymphocytes without affecting IL-2 receptor expression on PHA-stimulated cells. In ten healthy subjects opioid receptor agonists did not significantly affect mitogen-induced proliferation of lymphocytes, except for the inhibitory effect of 10(-8) M morphine in relation to lymphocytes stimulated with an optimal pokeweed mitogen (PWM) concentration. At the same time, opioid receptor agonists depressed surface IL-2 and Trf receptor expression on PHA-stimulated normal lymphocytes. In most of our experiments naloxone itself, a non-selective competitive opioid receptor antagonist, decreased mitogen-induced lymphocyte proliferation and IL-2 and Trf receptor expression on PHA-stimulated lymphocytes. Moreover, most frequently naloxone did not reverse inhibitory effects of opioid receptor agonists on lymphocytes. The results seem to indicate that opioid receptor stimulation by high metenkephalin concentrations, which are observed in the uremic blood plasma, may share the responsibility for immunodeficiency in chronic uremic patients. Next, in the presence of opioid receptor agonists directions of changes in the mitogen-induced proliferative response may not follow the alterations of IL-2 and Trf receptor expression on both uremic and normal lymphocytes. Finally the results also suggest that naloxone may possibly exert effects which are independent of its action on opioid receptors on lymphocytes.     

Soluble interleukin-2 receptor and disease activity in Crohn's disease.

An ELISA was used to measure concentrations of soluble interleukin-2 receptor (sIL-2R) alpha chain in the sera of patients with Crohn's disease. In a group of 56 patients, serum concentrations of sIL-2R were significantly raised in patients with active disease compared with patients with inactive disease and age-matched control populations. There was a significant correlation between serum sIL-2R concentration and disease activity as assessed by the Harvey-Bradshaw index (r = +0.60; P less than 0.001) and laboratory measurements of disease activity including C-reactive protein (r = +0.79; P less than 0.001), ESR (r = +0.64; P less than 0.001) and platelet count (r = +0.533; P less than 0.001). We also found a negative correlation between sIL-2R levels and serum albumin (r = -0.66; P less than 0.001). In longitudinal studies, changes in the concentration of serum sIL-2R reflected the changes in disease activity. Soluble IL-2R, therefore, offers a new measure of disease activity in Crohn's disease with a potential advantage over other laboratory parameters currently available in that it may reflect more accurately the underlying immunopathogenic process.     

High Serum-Soluble Interleukin-2 Receptor is not Associated with the Immunosuppression in Diffuse Cutaneous Leishmaniasis

Diffuse Cutaneous Leishmaniasis (DCL) is a rare complication of Leishmania aethiopica -induced cutaneous leishmaniasis which is associated with non-self healing and in vivo and in vitro antigen-specific non-responsiveness. Such antigen-specific unresponsiveness is also observed in visceral leishmaniasis (VL). The non-responsiveness seen in VL disease is believed to be due, in part, to serum-derived factors, including raised serum soluble IL-2 receptor (sIL-2R). Raised sIL-2R in serum was not a consistent feature of DCL in our study (range: 787–4546 U/ml) but was frequently observed in sera of patients with other dermatological disorders (range: 474–3313 U/ml) and some patients with the simple local cutaneous leishmaniasis (LCL; range: 556–4247 U/ml). The level of sIL-2R in the sera of DCL patients was not indicative of the disease state. Sera from DCL patients did not reduce proliferation of the IL-2-dependent CTLL cell line nor reduce PHA-driven mononuclear cell proliferation, although sera from VL patients could. Both DCL and VL sera could reduce the L. aethiopica -driven proliferation. Furthermore addition of serial dilutions of recombinant IL-2 to CTLL cultured in VL or DCL sera containing high sIL-2R levels did not alter the effect of such sera on proliferation. We conclude therefore, that raised sIL-2R in serum is not associated with the immunosuppression in DCL.     

Anti-CD3 antibody-induced expression of both p55 and p75 chains of the high affinity interleukin-2 receptor on human T lymphocytes is inhibited by cyclosporin A.

The inhibitory effect of cyclosporin (CsA) was investigated on human lymphocytes stimulated by anti-T-cell antibodies (anti-CD3 and -CD2) or mitogenic lectins. Whereas inhibition of cell proliferation (50%) occurred at 10 ng/ml CsA after cell activation via CD3 or CD2, higher CsA concentrations (300 ng/ml) were necessary to inhibit lectin-mediated cell activation (PHA, Con A). Exogenous recombinant interleukin-2 (rIL-2) partially reversed the inhibitory effect on antibody-stimulated cells only; however, at higher CsA concentrations (300 ng/ml) proliferation was again inhibited. Thus, CsA affected IL-2R expression and/or function at higher concentrations (300 ng/ml). CsA had no effect on receptor function as measured on IL-2-dependent cell growth of CTLL cells or preactivated lymphocytes. However, CsA inhibited both high and low affinity receptor expression as shown by [125I]IL-2 equilibrium binding studies on anti-CD3-stimulated cells. Cross-linking studies revealed that both p55 (TAC) and p75 chains of the IL-2R were not induced at low CsA concentrations (10 ng/ml). However, addition of rIL-2 reversed CsA inhibition of IL-2R expression. It is concluded that CsA, at least in anti-CD3-stimulated cells, inhibits IL-2R expression and cell proliferation with similar potency. Exogenous rIL-2 reverses CsA inhibition of IL-2R expression. This might be due to binding of rIL-2 to receptors which escape CsA inhibition, thereby up-regulating receptor expression which is drug resistant.     

Interleukin-4 regulates the interleukin-2 receptors on human peripheral blood B lymphocytes.

The high-affinity interleukin-2 (IL-2) receptor (IL-2R) consists of the non-covalent association of at least two subunits, p55 and p70-75, capable of binding IL-2 with low and intermediate affinity, respectively. We studied the effects of cytokines on the IL-2R expressed on human peripheral blood B lymphocytes using monoclonal antibodies specific for IL-2R p55 and IL-2R p70-75, by means of two-colour flow cytometric analysis. In freshly isolated peripheral blood B lymphocytes, the p55 subunit was expressed only in a small population (7.0% of CD20+ cells), whereas the p70-75 subunit was expressed in a large population (89.0% of CD20+ cells). Of the cytokines studied, interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) were involved in the regulation of IL-2R on B cells. After a 2-day incubation with IL-4, expression of IL-2R p55 was markedly induced, but expression of IL2-R p70-75 was profoundly suppressed in a dose-dependent manner. These abilities of IL-4 to promote IL-2R p55 expression and suppress IL-2R p70-75 expression were inhibited by the presence of IFN-gamma. Other cytokines, including IL-1, IL-2, IL-5, and IL-6, had little effect on the expression of these two subunits. These findings suggest that IL-4 is a cytokine modulating B cell response through the regulation of IL-2R.     

IL-2 regulation of soluble IL-2 receptor levels following thermal injury.

In the immunosuppressed burn patient serum levels of both IL-2 and a soluble form of IL-2 receptor alpha (sIL-2R alpha) are significantly elevated. Strikingly, the production of these markers by the in vitro activated patients' cells is decreased. This study examines the role of IL-2 in the decreased production of the sIL-2R alpha in vitro in patients with major burns (n = 18, 30 to greater than 70% total body surface area). Peripheral blood mononuclear cell (PBMC) cultures from patients with highly elevated serum sIL-2R alpha, and from healthy controls (n = 12) were activated with concanavalin A (Con A) at initiation. In patients' cultures mitogen-induced increments of sIL-2R alpha levels were significantly lower. There was a significant negative correlation (r = 0.64, P less than 0.001) between a high serum sIL-2R alpha level and a decreased lectin-induced sIL-2R alpha release in vitro. Low levels of sIL-2R alpha in patients' samples were not normalized by increasing the number of T lymphocytes. Also exogenous rIL-1 was without effect, whereas rIL-3 increased sIL-2R alpha release in some cultures. However, sIL-2R alpha levels were significantly increased in patients' cultures by (i) addition of exogenous IL-2; (ii) removal of adherent cells; (iii) addition of cyclooxygenase inhibitor, indomethacin; (iv) bypassing cell surface activation by the combination of the calcium ionophore A23187 and the phorbol ester 12-o-tetradecanoyl acetate. The cyclic AMP-elevating drug, forskolin, abrogated the ability of exogenous IL-2 to increase sIL-2R alpha production. Thus, in the burn patient, the reduced in vitro sIL-2R alpha release appears to relate to abnormalities in IL-2 production and action mediated through its functional surface receptor. Elevated levels of sIL-2R alpha in vivo may, therefore, reflect systemic activation of T lymphocytes in response to biologically active IL-2.     

Inhibition of IL-2R and SLA class II expression on stimulated lymphocytes by a suppressor activity found in homogenates of African swine fever virus infected cultures

Summary Virus free supernatants (VFS) obtained by ultracentrifugation of homogenates of African swine fever (ASF) virus infected cultures inhibited the proliferative response and the expression in peripheral blood mononuclear cells of two activation molecules, the IL-2 receptor (IL-2R) and the swine MHC class II antigens (SLA II), induced by several stimuli (lectins, PMA plus the calcium ionophore A23187 or specific antigen). This inhibition was time dependent: no effect was seen on IL-2R expression when VFS was added after 48 h, when the expression of this molecule reached its maximum. However at this time the proliferative response was still inhibited. The presence of VFS in the cultures was necessary to inhibit both the IL-2R expression and the proliferation of cells. In these conditions the addition of exogenous IL-2 to the cultures failed to restore the IL-2R expression and the proliferation shown by control stimulated cells. Furthermore, the IL-2 activity found in supernatants from cell cultures stimulated with Con A in the presence of VFS was even higher than in cultures stimulated without VFS. The inhibition observed suggests an important impairment of host immunocompetence in ASF infected swine.     

慢性肾功能衰竭患者血液透析前后白细胞介素2及其受体的变化

本文报道２０例作维持性血液透析的慢性肾功能衰竭患者，其血清ｓＩＬ－２Ｒ水平以及静息期和诱导后表达ｍＩＬ－２Ｒ的活化Ｔ淋巴细胞百分率，均明显高于正常人对照组，患者经一次血透后即时检测，ｓＩＬ－２Ｒ和静息期ｍＩＬ－２Ｒ两种指标的水平均呈显著降低。此外，血透后血中ＩＬ－２水平较血透前增高。结果提示，慢性肾功能衰竭患者存在ＩＬ－２及其相应受体水平的异常，而充分透析能予以部分纠正。     

Divergent effects of FcγRIIIA ligands on the functional activities of human natural killer cells in vitro

The Fcγ receptor (R)IIIA (CD16) plays an important role in regulating the cytotoxic and non-cytotoxic functions of human natural killer (NK) cells. Some anti-CD 16 monoclonal antibodies (mAb) have been shown to stimulate NK activity, while human monomeric (m) IgG induces dose-dependent inhibition of NK activity. To explore further these interactions mediated via FcγRIIIA, purified NK cells were cultured for 2–3 days in the presence of mIgG, 3G8 mAb, interleukin-2 (IL-2) or a combination of mIgG or 3G8 with IL-2. Binding of mIgG or 3G8 to FcγRIIIA induced divergent effects of functions of cultured NK cells: 3G8 mAb + IL-2 induced dose-dependent inhibition of proliferation attributable to apoptosis; in contrast, mIgG + IL-2 significantly increased NK cell proliferation. Incubation of NK cells in the presence of mIgG up-regulated expression of surface activation markers (CD69, IL-2Rα, ICAM-1), cytotoxicity, cytokine production (IL-1β, IFN-γ and TNF-α) and release of soluble IL-2R. Thus, mIgG binding to FcγRIIIA induced stimulatory signals in human NK cells, leading to up-regulation of IL-2Rα expression, cell proliferation and cytokine release.     

Recombinant interleukin-1 alpha inhibits the growth of rat mesangial cells in culture.

We have investigated the effect of interleukin-1 (IL-1) on the growth of mesangial cells isolated from rat kidney. Recombinant IL-1 alpha inhibited 3H-thymidine uptake by mesangial cells in a dose-dependent manner in the presence of either 0.5% or 5% fetal bovine serum (FBS). In the presence of high concentration of FBS (10%), the effect of IL-1 was not prominent. The inhibitory effect of IL-1 on the growth of mesangial cells was also confirmed by a change in cell numbers and measurements of protein synthesis with 3H-leucine. IL-1-induced inhibition of mesangial cell growth was not affected by indomethacin. IL-1 showed no effects on intracellular Ca2+ levels in mesangial cells. These observations indicate that IL-1 inhibits the growth of mesangial cells, and thus may play a protective role for mesangial cells from abnormal proliferation in some pathophysiological states.     

Changes in plasma levels of interleukin-2 receptor in relation to disease exacerbations and levels of anti-dsDNA and complement in systemic lupus erythematosus.

Interleukin-2 receptor (IL-2R) is expressed and released predominantly by activated T cells. In order to investigate whether disease exacerbations of systemic lupus erythematosus (SLE) are preceded by T cell activation, we prospectively measured levels of IL-2R once a month, from 6 months prior to exacerbations until 1 month afterwards. To assess the temporal relation between T cell activation and B cell activation, we measured, in addition, levels of anti-dsDNA, complement C3/C4, and total IgG. During a mean follow-up period of 23 months, 40 exacerbations occurred in 21 out of the 71 participating patients. For the present study one exacerbation per patient was evaluated. During exacerbation levels of IL-2R were increased in 18 out of the 21 cases and correlated with levels of anti-dsDNA (P less than 0.02), C3 (P less than 0.02), and C4 (P less than 0.01), but not with the score of the disease activity index. Levels of IL-2R rose prior to the exacerbation (P less than 0.02) and fell afterwards following treatment (P less than 0.05). Even in the absence of disease activity or during minor disease symptoms IL-2R levels were higher (P less than 0.01) than in healthy controls. Sixteen out of the 21 exacerbations (76%) were preceded by a significant increase in IL-2R. Changes in levels of anti-dsDNA and complement C3/C4 tended to precede changes in levels of IL-2R. We conclude that increased levels of IL-2R, compatible with T cell activation, are present in SLE already during inactive disease. These levels further increased prior to exacerbations of disease. As such, IL-2R is an indicator of disease activity in SLE. Serial measurement of IL-2R is a sensitive test for predicting disease exacerbations of SLE.     

Regulation of IL-2 beta receptor expression and beta-chain mRNA by human thymocytes.

The high affinity form of the human IL-2 receptor (IL-2R) has two known components, the IL-2R alpha (p55) and the IL-2R beta chain (p75). We have previously shown that recombinant IL-2 (rIL-2) could induce the expression of the alpha-chain (p55) on T cells and thymocytes, and increase this expression following suboptimal activation with concanavalin A (Con A) in combination with IL-2. An increase in the accumulation of IL-2R alpha-specific mRNA induced by rIL-2 in T cells and thymocytes had also been documented. We report here that the expression of IL-2R beta on the cell surface can be demonstrated on human thymocytes by the binding of Mik beta1, a MoAb directed against an epitope of the beta-chain. The IL-2R beta chain is constitutively expressed on freshly isolated thymocytes; this expression can be increased in thymocytes activated with Con A in combination with IL-2 or tetradecanoylphorbol 13-acetate (TPA). Blocking the formation of high affinity receptors with a MoAb directed against the alpha-chain of the receptor results in an increase in the display of IL-2R beta as evidenced by binding of MoAb Mik beta1. The accumulation of IL-2R-beta-specific mRNA is observed in freshly isolated thymocytes and it is increased in thymocytes cultured with rIL-2 alone, with Con A, and further enhanced by the addition of rIL-2 in combination with Con A or with TPA. Cyclosporine (CsA), which inhibits the accumulation of lymphokine-specific mRNA of thymocytes, does not inhibit the induction of the accumulation of IL-2R beta-specific mRNA. This is analogous to its effect on the expression of the alpha-chain (p55), and the accumulation of alpha-chain-specific mRNA.     

SLE患者T细胞和IL－2／IL－2R系统变化的临床意义

本文检测３７例（４１份）ＳＬＥ患者ＩＬ－２的产生、ｍＩＬ－２Ｒ的表达、ｓＩＬ－２Ｒ水平、淋巴细胞转化及Ｔ细胞亚群。结果表明：ＳＬＥ患者ｓＩＬ－２Ｒ水平升高，而ＩＬ－２的产生、ｍＩＬ－２Ｒ的表达、淋转率、ＣＤ４＋百分率和ＣＤ４＋／ＣＤ８＋比值均下降，由于其中仅有ｓＩＬ－２Ｒ水平与疾病活动性有关，因而ｓＩＬ－２Ｒ可作为疾病活动的一个指标。免疫指标的变化与激素治疗无关。本文认为Ｔ细胞功能及ＩＬ－２释放紊乱主要是由疾病本身的免疫调节紊乱引起。     

SLE患者T细胞和IL－2／IL－2R系统变化的临床意义

本文检测３７例（４１份）ＳＬＥ患者ＩＬ－２的产生、ｍＩＬ－２Ｒ的表达、ｓＩＬ－２Ｒ水平、淋巴细胞转化及Ｔ细胞亚群。结果表明：ＳＬＥ患者ｓＩＬ－２Ｒ水平升高，而ＩＬ－２的产生、ｍＩＬ－２Ｒ的表达、淋转率、ＣＤ４＋百分率和ＣＤ４＋／ＣＤ８＋比值均下降，由于其中仅有ｓＩＬ－２Ｒ水平与疾病活动性有关，因而ｓＩＬ－２Ｒ可作为疾病活动的一个指标。免疫指标的变化与激素治疗无关。本文认为Ｔ细胞功能及ＩＬ－２释放紊乱主要是由疾病本身的免疫调节紊乱引起。