The c-kit ligand potentiates the allogeneic mixed lymphocyte reaction

The allogeneic mixed lymphocyte reaction (MLR) is a complex in vitro assay of T-cell recognition and responsiveness in which interleukin-2 (IL-2) plays a central role. We have previously demonstrated that c-kit ligand (KL) can enhance IL-2-induced proliferation in a subset of human natural killer cells expressing the c-kit tyrosine kinase receptor. In the present study, we asked whether KL could enhance IL-2-mediated T-cell proliferation in the allogeneic MLR. We demonstrate that the vast majority of activated human T-cell clones express the c-kit mRNA transcript. Binding studies performed on activated T cells with radioiodinated KL were consistent with the expression of a single class of c-kit receptors. The addition of exogenous KL to the MLR led to an increase in tritiated thymidine (3[H]-TdR) incorporation in the absence of other exogenous cytokines, and did so in a dose-dependent fashion. A reproducible increase in 3[H]-TdR incorporation was noted at concentrations of KL, which approximate those normally found in vivo. Antibody blocking of KL binding to c-kit, T-cell depletion and sorting experiments suggest that the action of KL is mediated at least in part by a direct effect on both CD4+ and CD8+ T-cells. KL's enhancement of the MLR also requires the binding of IL-2 to its high-affinity IL-2 receptor. Given the abundance of KL normally found in human serum, these data suggest that this cytokine may have a role during T-cell activation in vivo.

Effects of methyl substitutions on benz[a]anthracene derivatives-induced immunosuppression

Polycyclic aromatic hydrocarbons are ubiquitous environmental contaminants known to be carcinogenic as well as immunosuppressive. Structure-activity studies have demonstrated that modifications in the number of methyl groups of benzanthracenic compounds lead to major changes in their biological activities such as induction of tumors. In the present study, we investigated the immunosuppressive effects of three benzanthracene derivatives differing by number or position of methyl radicals. 7,12-Dimethylbenz[a]anthracene, 12-methylbenz[a]anthracene, and 7-methylbenz[a]anthracene were tested for their ability to inhibit T-cell proliferation. For this purpose, we employed an in vitro activation model utilizing concanavalin A (ConA) or anti-CD3 monoclonal antibody (anti-CD3 mAb) to induce proliferation of murine T-lymphocytes from B6C3F1 mice. The three compounds inhibited splenocyte proliferation stimulated with anti-CD3 mAb, whereas DMBA and 12-MBA, but not 7-MBA, inhibited ConA-induced lymphoproliferation. Results concerning parameters involving interleukin-2 (IL-2) were correlated with those obtained for lymphoproliferation. IL-2 production and number of IL-2 receptors (IL-2R) per cell were inhibited by the three molecules tested, except for IL-2 production following ConA activation of cells treated with 7-MBA. Only DMBA profoundly affected IL-2 responsiveness, suggesting that this compound may inhibit both G0 to G1 and G1 to S transitions of the cell cycle. Addition of exogenous cytokines such as IL-1 and IL-6 with IL-2, or IL-2 alone, suggested that, for the three compounds tested, IL-1 and IL-6 production are not involved in benz[a]anthracene-induced immunosuppression. These results demonstrate that methylation at both 7 and 12 positions of the benzanthracene ring significantly enhances immunosuppression. In addition, DMBA may act on signal transduction mediated by the T-cell receptor (TCR) and the IL-2R, while this is not the case for 7-MBA and 12-MBA.

Differential regulation of interleukin-12- and interleukin-15-induced natural killer cell activation by interleukin-4

The regulation of human natural killer (NK) cell activation is under the control of a network of regulatory signals provided by cytokines. In the present study, we investigated the functional interaction between interleukin (IL)-4 and two monocyte/macrophage-derived cytokines, IL-12 and IL-15, during the process of NK stimulation. Using freshly isolated human NK cells, we have demonstrated that IL-4 negatively regulates lymphokine-activated killer (LAK) activity induced by IL-15 against the NK-resistant Daudi target cells. In contrast, IL-4 had no effect on IL-12-stimulated LAK generation. The differential effect of IL-4 on NK cell activation by IL-12 and IL-15 correlates with its ability to increase or to down-regulate the level of tumor necrosis factor-alpha and interferon-gamma release by NK cells, respectively. In contrast, endogenous transforming growth factor-beta 1 does not appear to be involved in the IL-4 regulatory pathway. Furthermore, while IL-4 was found to decrease the basal expression of the IL-2 receptor beta subunit utilized by IL-15, it had no effect on the expression of the beta 1 chain of the IL-12 receptor compared to untreated cells. Northern blot analysis indicated that the IL-4 regulatory effect on NK lytic function was associated with its capacity to down-regulate granzyme B and perforin gene transcription in response to IL-15 and its failure to affect the expression of both gene's in response to IL-12. Together, these data suggest the existence of a distinct cross-talk between IL-4 and IL-15 or IL-12 signaling pathways during the regulation of human non-major histocompatibility complex-restricted cytotoxicity.

Suppression of lymphocyte interleukin-2 receptor expression by glucocorticoids, cyclosporine, or both

Although glucocorticoids and cyclosporine are frequently used to treat patients with various types of glomerulopathy, clinical responses to treatment vary considerably. Considerable interindividual heterogeneity in the suppressive effects of glucocorticoids on lymphocyte proliferation in vitro has been previously reported, suggesting that differences in the pharmacodynamic responsiveness of the immune system to these agents might be an important determinant of how well an individual patient responds to treatment. It also has been shown that methylprednisolone is significantly more suppressive than prednisolone. To identify cellular mechanisms by which these drugs act, a study of the suppressive effects of prednisolone, methylprednisolone, and cyclosporine on lymphocyte proliferation and the expression of the cell surface receptor for interleukin-2 (IL-2R) was conducted using phytohemagglutin-stimulated peripheral blood mononuclear cells (PBMCs) from 13 patients with glomerulopathy and 12 control subjects. Heterogeneity among individuals in both parameters of lymphocyte responsiveness to these drugs was again found, and the significantly greater suppressive effect of methylprednisolone was confirmed for both proliferation and IL-2R expression in patients and control subjects. Cyclosporine alone was moderately suppressive. For most individuals, the greatest degree of suppression occurred when cells were exposed to both cyclosporine and glucocorticoid. Further studies are being conducted to determine whether pretreatment assessment of in vitro lymphocyte responsiveness has any predictive value regarding therapeutic efficacy of each drug in individual patients and to identify of those patients likely to require a more intensive or multidrug immunosuppressive regimen.

Ligand-induced autoregulation of IL-2 receptor alpha chain expression in murine T cell lines

The IL-2 receptor (IL-2R) is composed of three chains alpha, beta and gamma. In mice, contrary to the human system, we have previously demonstrated that the IL-2R beta gamma complex does not bind IL-2. Therefore, mouse IL-2 response is completely dependent on the expression of the IL-2R alpha gene product. T cell clones expressing mouse IL-2R beta gamma and the human IL-2R alpha transgene have been studied. When cells are grown in IL-4, mouse IL-2R alpha is not expressed. However, exposure to IL-2 leads to the expression of the endogenous murine IL-2R alpha subunit. The T cell line expressing mouse IL-2R gamma and human IL-2R beta can grow in IL-2 but does not express endogenous murine IL-2R alpha. Transfection of these cells with the human IL-2R alpha gene restores the capacity to induce murine IL-2R alpha. This result demonstrates that IL-2-IL-2R alpha interactions are required for induction of IL-2R alpha. The kinetics of induction and deinduction of murine IL-2R alpha have been studied using clone 18.III. From negative cells, expression of murine IL-2R alpha is a very slow phenomenon. From cells fully expressing IL-2R alpha, deinduction is a two-step process: after a rapid decrease of IL-2R alpha the cells continue to express, for a long period of time, basal levels of murine IL-2R alpha. When cells expressing basal levels of IL-2R alpha are exposed to IL-2, induction of IL-2R alpha is a very rapid phenomenon. The autoregulatory loop formed by IL-2-IL-2R alpha therefore displays different levels of functioning.

Clonal and functional analysis for the augmentation of tumour-infiltrating lymphocytes by interleukin 4

In the adoptive immunotherapy for cancer, the amounts of induced effector cells play a major role in improving therapeutic efficacy. We have already demonstrated that interleukin 4 (IL-4) augments proliferation of tumour-infiltrating lymphocytes (TILs) without altering the cytotoxic activity against autologous tumour cells. The present study is designed to investigate how IL-4 augments TILs by using established TIL clones in terms of IL-2/IL-2 receptor system. CD4+, CD8+ and CD4+ CD8+ (double positive) TIL clones were established from cancer patients. At clonal level, IL-4 augmented the proliferation of IL-2-activated TIL clones irrespective of phenotypes. In order to clarify the mechanism of IL-4 at clonal level, the blocking assay by anti-IL-2 receptor alpha and beta chain and binding assay of IL-2 on the cell surface and the measurement of the internalisation of IL-2 in the cell were performed. It was clarified that IL-4 up-regulated the IL-2 receptor and then augmented the action of IL-2 molecule on the cell surface stimulated by IL-4. Furthermore, binding IL-2 internalised rapidly into the cells. Thus, it is suggested that signal transduction is augmented and proliferation of TILs is enhanced by IL-4 via the action of IL-2/IL-2 receptor system.

Characterization of a ricin fusion toxin targeted to the interleukin-2 receptor

Fusion toxins are hybrid proteins consisting of peptide ligands linked through amide bonds to polypeptide toxins. The ligand directs the molecule to the surface of target cells and the toxin enters the cytosol and induces cell death. Ricin is an excellent candidate for use in fusion toxins because of its extreme potency, the extensive knowledge of its atomic structure and the lack of prior immunological exposure in patients. We synthesized a baculovirus transfer vector with the polyhedrin promoter followed sequentially from the 5' end with DNA encoding the gp67A leader sequence, the tripeptide ADP, IL-2 (interleukin-2), another ADP tripeptide and RTB (ricin toxin B chain) with lectin-site mutations W37S and Y248H. Recombinant baculovirus was generated in Sf9 insect cells and used to infect Sf9 cells. Recombinant IL-2-RTB[W37S/Y248H] protein (fusion protein of IL-2 with modifications W37S and Y248H) was recovered at high yields from day 6 insect cell supernatants, partially purified by affinity chromatography and reassociated with RTA (ricin toxin A chain). The fusion toxin was soluble, immunoreactive with antibodies to RTB, IL-2 and RTA and had a molecular weight of 80 kDa by SDS-PAGE. The molecule reacted poorly with asialofetuin, but bound strongly to IL-2 receptor based on selective cytotoxicity to IL-2 receptor bearing cells. The specific cytotoxicity could be blocked with IL-2 but not lactose. Thus, we report a novel targeted fusion toxin protein with full biological activity.

Interleukin-2 receptor-specific fusion toxin inhibits barotrauma-induced arterial atherosclerosis

Immunocytochemical analyses of human plaques and experimental arterial lesions have implicated activated lymphocytes and monocytes in the pathogenesis of atherosclerosis, as demonstrated by the expression of interleukin-2 (IL-2) membrane receptors and major histocompatibility complex class II epitopes. The objective is to determine if targeting these cells with an IL-2 receptor-specific chimeric toxin, DAB486-IL-2, can inhibit experimental post-angioplasty vascular neointimal thickening. Twenty-two atherogenically modeled rabbits were treated in vivo with DAB486-IL-2 (0.1 mg/kg per day i.v.; n = 11) or placebo (n = 11) for 10 days following aortic balloon angioplasty (4 atm x 30 s each x 2 dilatations). In vitro 3H-leucine incorporation studies of mononuclear leukocyte and vascular smooth muscle cell protein synthesis inhibition by DAB486-IL-2 were also performed. Angioplasty sites were examined for evidence of hyperproliferative atherosclerotic narrowing by quantitative angiography and histomorphometry of neointimal cross-sectional area at baseline and 6 weeks after injury. In vitro Concanavalin-A stimulated rabbit mononuclear leukocyte protein synthesis was 50% inhibited by DAB486-IL-2 at a concentration (IC50) of 6 x 10(-11) M. Rabbit vascular smooth muscle cells were approximately 150-fold less sensitive to DAB486-IL-2 (IC50 = 10(-8) M). In vivo studies showed no change in angioplasty site angiographic minimum luminal diameter at 6 weeks in DAB486-IL-2 treated animals (from 2.96 +/- 0.52 to 2.96 +/- 0.48 mm; percent cross-sectional area reduction = 1 +/- 10%; P = N.S.). In control animals, luminal diameter decreased from 2.79 +/- 0.4 to 2.32 +/- 0.52 mm at 6 weeks, and percent cross-sectional area was reduced by 34 +/- 14% (P < 0.01 vs. placebo). Quantitative histomorphometric angioplasty segmental intimal cross-sectional area reduction of treated and placebo vessels also differed significantly (19 +/- 16% vs. 31 +/- 21%; P < 0.05). DAB486-IL-2 caused no adverse effects on animal survival, weight or hepatic transaminase levels. We conclude that post-angioplasty administration of the chimeric toxin DAB486-IL-2 inhibits angiographic narrowing and neointimal thickening in the atherogenic rabbit model. Although this IL-2 receptor-specific molecule was cytotoxic in vitro for activated mononuclear leukocytes and vascular smooth muscle cells, systemic toxicity did not occur in vivo at a dose comparable to that evaluated in clinical trials of this agent. Potential anti-proliferative effects of this chimeric toxin may be mediated by direct local inhibition of leukocyte-mediated inflammation, or through the indirect modification of vascular cell mitogenesis and cytokine release.

Effect of recombinant human interleukin 2 on neutrophil adherence to endothelial cells in vitro

Human neutrophils were demonstrated to possess interleukin-2 receptor (IL-2R) beta and gamma chains, not alpha chain and the binding of IL-2 to the IL-2R beta chain on neutrophils plays an important regulatory role in neutrophil functions. We have investigated in this study the hypothesis that recombinant human IL-2 (rhIL-2) can directly activate human neutrophils and increase their adherence to human umbilical vein endothelial cells (HUVEC). In an in vitro microtiter adherence assay, rhIL-2 significantly stimulated neutrophil adherence to HUVEC in a dose- and time-dependent manner, rhILI-2 concentration at 2000 u/ml and 2 hour incubation gave the best neutrophil stimulation. Treatment of neutrophils with rhIL-2 increased the expression of adhesion molecule CD18. Pretreatment of the stimulated neutrophils with a blocking monoclonal antibody to CD18 decreased but not completely blocked the adherence of neutrophils to HUVEC. These data suggest than rhIL-2 can directly stimulate and increase neutrophil adherence to HUVEC by enhancing the expression of CD18 and possibly other adhesion molecules on neutrophil surface. This may be a critical step in the early stage of the vascular leak syndrome (VLS) associated with high dose IL-2 therapy.

Influence of anticoagulants on the level of soluble HLA class I and class II antigens measured in blood samples

The existence of soluble forms of HLA class I and class II antigens in human serum is well established and altered concentrations of these serum proteins have been described to be associated with various diseases. Since soluble HLA antigens (sHLA) can be measured both in serum and plasma samples, we investigated whether anticoagulant treatment influences the determined levels of soluble HLA class I (sHLA-I) or soluble HLA-DR (sHLA-DR). Analyzing paired samples of serum and plasma of 40 healthy individuals we found significantly lower serum levels of sHLA-DR (0.31 +/- 0.15 ng/ml) compared to EDTA plasma levels (0.58 +/- 0.20 ng/ml). By contrast, serum levels of sHLA-I (0.89 +/- 0.74 micrograms/ml) were only slightly lower than EDTA plasma values (0.95 +/- 0.86 micrograms/ml), a situation similar to that of sIL-2R and sCD4 levels. Further experiments intended to clarify the reasons of the reduced sHLA-DR serum levels revealed that (i) the blood storage time before centrifugation did not influence the sHLA-DR level, (ii) treatment of serum with anticoagulant did not augment the measured sHLA-DR concentration, and (iii) the recovery of spiked sHLA-DR was significantly lower when added to native blood than to serum or anticoagulant-treated blood. These results suggest that sHLA-DR is partly removed by the process of blood clotting thus resulting in diminished sHLA-DR serum levels.

Immunosuppressive activity of bovine seminal ribonuclease and its mode of action

Two preparations of dimeric BS RNase-native and recombinant proteins caused identical immunosuppressive effects on MLC-stimulated human lymphocytes. The monomers of RNase A and BS RNase were ten times less active. The inhibitory effect on MLC-stimmulation was followed by 90% inhibition of cell-mediated lympholysis (CML) caused by BS RNase (10 micrograms/ml). This effect indicated that BS RNase suppressed the recognition phase of the cytotoxic reaction, resulting in inhibition of generation of cytotoxic effector cells. BS RNase exerted a similar effect on generation of cytotoxic LAK cells. Cytotoxic activity of LAK cells or CTLs against K562 target cells was abrogated only when BS RNase was added at the beginning of the sensitizing phase, but the cytotoxicity of effector cells in the destruction phase was not influenced. The effect of RNase A on the generation of cytotoxic cells was much less pronounced. To get more information about the site of action, the effect of BS RNase on early lymphocyte stimulation by PHA was investigated by using fluorescein cell probes. BS RNase (100 micrograms/ml) prevented a shift in fluorescein emission occurring within one hour of activation using fluorescein diacetate as a marker for changes in the cytoplasmic matrix. On the contrary, it did not block the shift in fluorescence emission when tested with diphenylhexatrien as a marker for changes in membrane fluidity. Furthermore the effect of BS RNase on expression of membrane antigens expressed on activated human lymphocytes was estimated. BS RNase significantly inhibited the expression of CD25, CD38 and CD71 antigens on PHA-, Con A- and MLC-stimulated human T and B lymphocytes. No substantial change in expression of these antigens was observed on IL-2-stimulated cells, but DNA synthesis was totally abrogated. These results indicate that the mode of action of BS RNase on activated T and B lymphocytes is based mainly on the suppressed expression of receptors for interleukin-2-alpha-chain and transferrin.

Inhibition of human T lymphoblast proliferation by hydroquinone

Hydroquinone (HQ) is a major metabolite of benzene and is present in large quantities in cigarette tar as a result of the combustion of tobacco leaf pigments. We hypothesize that the immunosuppressive effects of cigarette smoking are due, in part, to the deposition of large quantities of HQ in the lungs. Exposure of primary human T lymphoblasts (HTL) in vitro to 50 microM HQ blocked IL-2-dependent proliferation by > 90% with no loss in viability. Inhibition of DNA synthesis was observed immediately after the addition of HQ to the cells. However, this effect could be reversed up to 6 hr later by simply washing the cells and reculturing them in the absence of HQ. HQ did not significantly alter intracellular glutathione levels up to 24 hr later, and the presence of 50 microM 2-mercaptoethanol or 500 microM dithiothreitol during the treatment did not prevent inhibition of DNA synthesis. HQ did not block binding of 125I-IL-2 to the cells, but inhibited the IL-2-dependent progression of HTL through S phase of the cell cycle. These observations demonstrate that HQ, in concentrations comparable to those found in cigarette tar, is a potent inhibitor of IL-2-dependent T cell proliferation and may therefore help to explain the potent immunosuppressive effects of cigarette smoke on lung T lymphocytes.

Mechanisms in interleukin-2 protection against glucocorticoid-induced apoptosis: regulation of AP-1 and glucocorticoid receptor transcriptional activities

We have used the gibbon ape leukemia cell line MLA-144 and its corticoid-sensitive subclone MLA-E7T to analyze the mechanisms whereby interleukin-2 (IL-2) can protect T cells against dexamethasone-induced apoptosis. MLA cells are characterized by the constitutive expression of intermediate affinity receptors for IL-2, together with IL-4 receptors. MLA-144 cells secrete IL-2 and are insensitive to dexamethasone, whereas MLA-E7T cells do not constitutively produce significant amounts of IL-2 and undergo apoptotic cell death in the presence of dexamethasone. Exogenous IL-2 was shown to protect MLA-E7T cells against the apoptotic effect of dexamethasone and to increase both the DNA binding and transactivating functions of activator protein-1 (AP-1). The functional relationship between AP-1 and glucocorticoid receptors transcriptional activities was further investigated using transient expression of reporter gene constructs whose transcriptions are regulated by promoters containing TPA-responsive elements or glucocorticoid-responsive elements. The data reported here demonstrate that in MLA-144 cells, IL-2 or PMA stimulation antagonizes the glucocorticoid receptor, whereas in MLA-E7T, synergistic effects are observed between dexamethasone and IL-2 or PMA for transactivation of MMTV-CAT. Taken together with the finding that IL-2 but not PMA protects MLA-E7T from dexamethasone-induced apoptosis, our results indicate that IL-2 does not induce such a protection by repressing the transcriptional activity of the glucocorticoid receptor.

Pre-B acute lymphoblastic leukemia cells may induce T-cell anergy to alloantigen

Even if neoplastic cells express tumor associated antigens they still may fail to function as antigen presenting cells (APC) if they lack expression of one or more molecules critical for the induction of productive immunity. These cellular defects can be repaired by physiologic activation, transfection, or fusion of tumor cells with professional APC. Although such defects can be repaired, antitumor specific T cells may still fail to respond in vivo if they may have been tolerized. Here, human pre-B cell acute lymphoblastic leukemia (pre-B ALL) was used as a model to determine if primary human tumor cells can function as alloantigen presenting cells (alloAPC) or alternatively whether they induce anergy. In the present report, we show that pre-B cell ALL express alloantigen and adhesion molecules but uniformly lack B7-1 (CD80) and only a subset express B7-2 (CD86). Pre-B ALL cells are inefficient or ineffective alloAPC and those cases that lack expression of B7-1 and B7-2 also induce alloantigen specific T-cell unresponsiveness. Under these circumstances, T-cell unresponsiveness could be prevented by physiologic activation of tumor cells via CD40, cross-linking CD28, or signaling through the common gamma chain of the interleukin-2 receptor on T cells. Taken together, these results suggest that pre-B ALL may be incapable of inducing clinically significant T-cell-mediated antileukemia responses. This defect may be not only due to their inability to function as APC, but also due to their potential to induce tolerance. Attempts to induce clinically significant antitumor immune responses may then require not only mechanisms to repair the antigen presenting capacity of the tumor cells, but also reversal of tolerance.

Supplementation with selenium augments the functions of natural killer and lymphokine-activated killer cells

This study examined the effects of dietary (2.0 ppm for 8 wk) and in vitro (1 x 10(-7)M) supplementation with selenium (Se, as sodium selenite) on the activity of spleen natural killer (NK) cells and plastic-adherent lymphokine-activated killer (A-LAK) cells from C57B1/6J male mice. Dietary supplementation with Se resulted in a significant increase in the lytic activity of activated NK cells, and cells from these highly lytic effector cell populations expressed significantly higher numbers of intermediate affinity interleukin-2 receptors (II-2R)/cell. In the presence of high concentrations of II-2 and 1 x 10(-7)M Se, resting populations of spleen NK cells developed into A-LAK cells that had a significantly enhanced ability to proliferate, as indicated by the significantly higher amounts of nuclear 3H-thymidine incorporation, and a significantly augmented cytolytic activity against both NK-sensitive and NK-resistant target cells. Se appears to enhance the lytic activity of activated NK cells and to augment the proliferation, expansion, and lytic activity of A-LAK cells in the presence of high concentrations of II-2 through its ability to enhance the expression of intermediate affinity II-2R on these cells.

Suppression of interleukin-2 receptor expression on mouse CD4+ T cells by bovine kappa-caseinoglycopeptide

Bovine kappa-caseinoglycopeptide (residues 106-169, CGP) completely inhibited the PHA-induced proliferation of mouse splenocytes when CGP was added simultaneously with PHA. The inhibitory effect, however, was reduced to about one-half when CGP was added after 24 h of cultivating the splenocytes with PHA or when anti-IL-1ra antibody was added simultaneously with PHA and CGP. On the other hand, CGP bound to mouse CD4+ T cells but not to CD8+ T cells. CGP suppressed IL-2 receptor expression of the PHA-stimulated mouse CD4+ T cells.

Interleukin 4 (IL-4) blocks the IL-2-induced increased in natural killer activity and DNA synthesis of decidual CD16-CD56bright NK cells by inhibiting expression of the IL-2 receptor alpha, beta, and gamma

The natural killer (NK) activity and DNA synthesis of decidual CD16-CD56bright NK cells were markedly elevated by treatment with interleukin 2 (IL-2). IL-4 did not affect NK activity or DNA synthesis of decidual CD16-CD56bright NK cells, but inhibited the IL-2-induced NK activity and DNA synthesis in a dose-dependent manner. Flow cytometry of decidual mononuclear cells cultured in IL-2 or IL-4 or both IL-2 and IL-4 demonstrated IL-4 inhibition of the expression of the IL-2 receptor alpha (IL-2R alpha), IL-2R beta, and IL-2R gamma on decidual CD16-CD56bright NK cells. This suggests that IL-4 blocks the IL-2-induced NK activity and DNA synthesis of decidual CD16-CD56bright NK cells by inhibiting the expression of IL-2R alpha, IL-2R beta, and IL-2R gamma.

Dehydroepiandrosterone sulfate is positively correlated with soluble interleukin 2 receptor and soluble intercellular adhesion molecule in systemic lupus erythematosus

OBJECTIVE

To determine whether dehydroepiandrosterone sulfate (DHEAS) is linked with soluble immune mediators in systemic lupus erythematosus (SLE).

METHODS

DHEAS and various soluble immune mediators were measured by ELISA in the serum of 35 patients with SLE (26 women, 9 men) and in 41 control subjects.

RESULTS

DHEAS was lower in patients with SLE compared to controls (male 1.29 +/- 0.32 vs 3.04 +/- 0.33 micrograms/ml, p < 0.001; female 0.75 +/- 0.12 vs 2.16 +/- 0.18 micrograms/ml, p < 0.001). The DHEAS reduction was in part dependent on prior glucocorticosteroid treatment (p < 0.02). After adjustment for multiple comparisons, there was significant negative correlation between steroid dose and DHEAS (RRank = -0.426, p = 0.005), but with none of the soluble immune mediators. No significant difference in the percentage of steroid treated male and female patients was found (p = 0.220). However, there was positive correlation between DHEAS and soluble interleukin 2 receptor in women, but not in men, with SLE [RRank = 0.747 (n = 26, p < 0.0001) vs RRank = -0.1333( n = 9, p = 0.366)] and between DHEAS and soluble intercellular adhesion molecule in women, but not in men, with SLE [RRank = 0.509 (n = 26, p = 0.005) vs RRank = 0.4833 (n = 9, p = 0.094)].

CONCLUSION

These data demonstrate positive interrelation between DHEAS and soluble immune mediators involved in leukocyte function and leukocyte adhesion only in female patients with SLE.

Halothane inhibits T cell proliferation and interleukin-2 receptor expression in rats

In order to determine the effects of halothane on rat cell-mediated immune function, rats were exposed to 1% halothane for up to 5 hours. Immediately, 24 hours or 48 hours following anesthesia, rat lymphocytes from the spleen were analyzed for their ability to respond to the mitogens phytohemagglutinin (PHA), pokeweed mitogen (PWM), concanavalin A (ConA) and lipopolysaccharide (LPS). In addition, percentages of lymphocyte subpopulations in the spleen were assessed as well as ability of the lymphocytes to express specific receptors. Extended periods of halothane anesthesia (5 hours) suppressed the ability of the lymphocytes to respond to the mitogen PHA immediately following anesthesia. Twenty-four hours later, proliferative responses to the mitogens PHA, PWM and ConA were significantly reduced. However, by 48 hours following treatment, proliferative responses were normal. Halothane did not alter proliferative responses to the mitogen LPS. Prolonged anesthesia (5 hours) also increased the percentage of T and CD8+ (cytotoxic) lymphocytes in the spleen, although for less than 24 hours. The ability of T lymphocytes to express both the CD8 and CD25 (IL-2) receptors in response to PHA were suppressed. These results suggest that halothane suppresses rat T cell function, perhaps through suppression of IL-2 receptor expression.

Soluble CD40 ligand induces expression of CD25 and CD23 in resting human tonsillar B lymphocytes

In this report, we describe the dose-dependent increase in both CD25 and CD23 levels on resting human B cells in response to CD40 ligation, as mediated by soluble CD40 ligand (sCD40L) or anti-CD40 antibody. In combination with interleukin (IL)-4, sCD40L had limited additive effects on CD25 expression, but significantly enhanced CD23 expression on tonsillar B cells. Interferon-gamma (IFN-gamma) exerted no inhibitory effect upon increases in CD25 or CD23 driven by CD40 ligation with sCD40L or anti-CD40 antibody. These data suggest that the induction of CD25 and CD23 genes by IL-4 is mediated, at least in part, by an IFN-gamma-sensitive component, whereas gene activation driven via CD40 ligation involves signaling pathways which are not sensitive to IFN-gamma.

Interleukin-15 promotes the growth of leukemic cells of patients with B-cell chronic lymphoproliferative disorders

The recently discovered cytokine, interleukin-15 (IL-15), has been demonstrated to share several biologic properties with IL-2 in different cell systems, including T-cell and natural killer (NK) cell compartments. As for B lymphocytes, IL-15 has been shown to provide stimulatory activities in normal preactivated B cells that are mainly transduced through IL- 2 receptor (IL-2R) complex components. Since leukemic B cells from patients with chronic lymphoproliferative disorders (CLD) bear IL-2R and grow in response to IL-2, we investigated whether IL-15 triggers the proliferation of malignant B cells obtained from 12 patients with B-cell chronic lymphocytic leukemia (B-CLL) and five patients with hairy cell leukemia (HCL). Enriched B cells recovered from five healthy subjects were also studied as controls. IL-15 stimulated the proliferation of freshly isolated leukemic B cells, but not resting normal B lymphocytes, the latter being able to grow in the presence of IL-15 only after in vitro preactivation with phorbol myristate acetate. The proliferation elicited by IL-2 on leukemic cells was comparable to that determined by IL-15. Following addition of graded concentrations of IL-15 to low/intermediate-dose IL-2, resting leukemic B cells showed a higher stimulatory rate than that observed using the two cytokines separately. In normal resting B lymphocytes, this cumulative effect was not observed. The role of different IL-2R subunits in IL-15-driven growth of malignant B cells was investigated both by their expression on leukemic cells and by the block of different IL-2R subunits (p55, p75, and p64) with specific monoclonal antibodies (MoAbs). Using flow cytometry and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses we demonstrated that both B-CLL and HCL leukemic B cells express the beta and gamma chains of the IL-2R system. The stimulatory activity achieved by IL-15 decreased significantly, blocking the beta and gamma chains of the IL-2R. Taken together, these findings demonstrate that IL-15 triggers the growth of leukemic B cells through IL-2R system subunits, pointing to the role of this novel cytokine in regulating the neoplastic proliferation in CLD.

Effect of ethanol and cocaine treatment of the immune system of v-Ha-ras-transgenic mice

The objective was to investigate if the presence of the v-Ha-ras oncogene could induce immune changes different to the ones observed in normal mice. Therefore, we decided to use Oncomice, the transgenic mice with an activated v-Ha-ras oncogene under the control of the mouse mammary tumor virus-promoter, and their normal inbred counterparts, FVB mice. Both strains of mice were fed the Lieber-DeCarli liquid diet with ethanol or the isocaloric control diet and were injected daily with cocaine or saline. The percentage and absolute number of T and B lymphocytes in the spleen and thymus were determined. The in vitro production of TNF-alpha (tumor necrosis factor-alpha), IL-2 (interleukin-2) and IFN-gamma (interferon-gamma) by spleen cells, and the levels of serum sIL-2R (soluble IL-2 receptor) were also measured. Oncomice fed the Lieber-DeCarli ethanol diet or receiving either saline or cocaine injections presented a higher tumor incidence than Oncomice receiving the control diet. A reduced total number of thymocytes as well as absolute number of cells in all the subsets was found in Oncomice. Moreover, a decreased percentage of CD8+ cells was also observed in Oncomouse spleens. These features were even more marked in ethanol-treated Oncomice. Higher serum sIL-2R levels were observed in Oncomice, especially in mice treated with ethanol or cocaine. The results suggest that the oncogene product, P21ras, plays an important role in dysregulating the immune system and hence in favoring tumorigenesis.

A multicenter trial of recombinant human interferon gamma in patients with systemic sclerosis: effects on cutaneous fibrosis and interleukin 2 receptor levels

OBJECTIVE

To evaluate the acute toxicity, potential efficacy, and effects on the soluble interleukin 2 receptor (sIL-2R) of recombinant human interferon gamma (rIFN-gamma) in patients with systemic sclerosis (SSc).

METHODS

A multicentered, pilot clinical trial of rIFN-gamma was performed on 20 patients (15 women, 5 men, mean age 45 years) with active cutaneous SSc (mean disease duration 36 months) to evaluate it potential as a novel therapy for this untreatable disorder. After one week of rIFN-gamma 0.01 mg/m2/day, subjects self-administered rIFN-gamma 0.1 mg/m2/day intramuscularly for a total of 18 weeks. The major outcome variable was a modified skin score (0 = normal skin, 3 = hidebound skin) measured and summed from 15 anatomic areas of the body. sIL-2R levels were measured by ELISA at entry and exit from the study.

RESULTS

The clinical results were modest at best. Nine of 20 patients achieved at least a 20% reduction in skin score, with one patient showing almost total remission of all skin abnormalities. The mean skin score at entry for all subjects was 22.8 +/- 8.9 and over the course of the trial improved marginally compared to baseline (mean change -4.72 +/- 6.62; p = 0.008). However, 8 subjects did not change appreciably while in the trial. Antibodies to Scl-70 were observed in only 5 patients (all with diffuse scleroderma) and were not associated with either response to or complications from therapy. The adverse reactions were frequent and occasionally severe. Ten subjects were withdrawn because of exacerbation of Raynaud's symptoms (n = 5), constitutional symptoms (n = 2), development of renal crises (n = 2), and mild pancytopenia (n = 1). Minor laboratory abnormalities were common and included elevation of cholesterol, triglycerides, hepatic transaminases, and reduction in white blood cell count. Compared to controls, mean sIL-2R was markedly elevated at entry (1309 +/- 495 U/ml; p = 0.0001) and did not change appreciably at exit. Spearman correlation analysis showed a trend but no statistically significant association of skin score with sIL-2R (R = 0.408; p = 0.074). However, sIL-2R was significantly correlated with erythrocyte sedimentation rate (R = 0.542; p = 0.0165). A subset analysis revealed that skin score (p = 0.0001) and sIL-2R (p = 0.00170) were significantly higher at baseline for patients with diffuse scleroderma compared to patients with limited disease.

CONCLUSION

rIFN-gamma may be beneficial for some patients with SSc, but the benefit appears marginal for most individuals and the side effects frequent. Although sIL-2R was elevated in many of the patients with SSc, it did not appear to be correlated with activity of cutaneous disease or response to therapy.

Association of immunological changes with clinical efficacy in atopic eczema patients treated with traditional Chinese herbal therapy (Zemaphyte)

The efficacy of the Chinese herbal therapy (Zemaphyte) has been well established as a treatment for atopic eczema (AE) in clinical trials. The purpose of this study was to probe the immunological changes that occurred when patients were treated with the herbs for a period of 8 weeks. This treatment decreased serum IgE complexes (p less than 0.05) but did not affect total serum IgE or CD23 expression on peripheral blood monocytes. Peripheral blood mononuclear cells from patients before and after treatment were cultured overnight with interleukin 4 and the ability of this cytokine to induce CD23 on monocytes from treated patients was found to be significantly diminished (p less than 0.01). Soluble interleukin 2 receptor and soluble vascular cell adhesion molecule were both raised in the serum of AE patients compared to control individuals. Both these parameters were decreased following treatment (p less than 0.05). All these changes coincided with improvement in erythema and surface damage scores. There was no alteration in soluble intracellular adhesion molecule or soluble CD23. The results of these investigations would suggest that this herbal treatment has the ability to target various immunological parameters which may be involved in the pathogenesis of AE.