Express Interleukin-2 Receptors Research Articles

CD122-targetted IL-2 signals cause acute and selective apoptosis of B cells in Peyer\u2019s Patches

Interleukin-2 (IL-2) has both pro- and anti-inflammatory properties that have been harnessed clinically and that are used experimentally to modulate leukocyte subsets in vivo. In mice, the bioavailability and half-life of IL-2 in vivo can be increased by complexing recombinant IL-2 with different clones of anti-IL-2 monoclonal antibodies that differentially target the cytokine to cells expressing different kinds of IL-2 receptors. While the impacts of systemic IL-2: anti-IL-2 antibody complex (IL-2C) administration are well-defined in the spleen and peripheral lymph nodes, how immune cells in the gut and gut-associated lymphoid tissues respond to IL-2C is not well characterized. Here, we analyze how major leukocyte populations in these tissues respond to IL-2C. We find that IL-2C targeting cells expressing IL-2 receptor beta cause an acute decrease in cellularity of Peyer’s Patches while cell numbers in the lamina propria and intraepithelial lymphocytes are unaffected. Cell contraction in Peyer’s Patches is associated with the apoptosis of multiple B cell subsets. Our results are important to consider for understanding off-target impacts of IL-2C regimes in experimental models and for considering how IL-2 may contribute to the etiology or severity of gut-associated conditions such as Crohn’s Disease.

Measurement of the concentration of serum soluble interleukin-2 receptor alpha chain in dogs with lymphoma

Soluble interleukin-2 receptor (sIL-2r) is released directly from the surface of lymphocytes expressing interleukin-2 receptor alpha chain (CD25), and its serum concentration has been found to reflect the prognosis of human lymphoproliferative malignancies. In this study, we demonstrated the presence of sIL-2r in canine serum and developed a specific sandwich enzyme-linked immunosorbent assay (ELISA) to quantify the concentration of canine serum sIL-2r. In the immunoprecipitation (IP) assay, CD25 protein weighing approximately 45 kDa was detected in canine serum, smaller than the membrane-bound CD25 (approximately 55 kDa). To measure the concentration of serum sIL-2r in dogs, an ELISA system was developed. Serum sIL-2r levels were significantly higher in dogs with multicentric high-grade B-cell lymphoma before therapy than that in healthy dogs. Serum sIL-2r concentration was also found to be elevated in a proportion of dogs with other types of lymphoma. Changes in serum sIL-2r levels generally paralleled the changes in mass and lymph node size in dogs with high-grade B-cell lymphoma. This study demonstrated that serum sIL-2r level would be a marker to monitor tumour growth and regression in canine lymphoma.

A Modified γ-Retrovirus Vector for X-Linked Severe Combined Immunodeficiency

BackgroundIn previous clinical trials involving children with X-linked severe combined immunodeficiency (SCID-X1), a Moloney murine leukemia virus–based γ-retrovirus vector expressing interleukin-2 receptor γ-chain (γc) complementary DNA successfully restored immunity in most patients but resulted in vector-induced leukemia through enhancer-mediated mutagenesis in 25% of patients. We assessed the efficacy and safety of a self-inactivating retrovirus for the treatment of SCID-X1.MethodsWe enrolled nine boys with SCID-X1 in parallel trials in Europe and the United States to evaluate treatment with a self-inactivating (SIN) γ-retrovirus vector containing deletions in viral enhancer sequences expressing γc (SIN-γc).ResultsAll patients received bone marrow–derived CD34+ cells transduced with the SIN-γc vector, without preparative conditioning. After 12.1 to 38.7 months of follow-up, eight of the nine children were still alive. One patient died from an overwhelming adenoviral infection before reconstitution with genetically modified T cells. Of the remaining eight patients, seven had recovery of peripheral-blood T cells that were functional and led to resolution of infections. The patients remained healthy thereafter. The kinetics of CD3+ T-cell recovery was not significantly different from that observed in previous trials. Assessment of insertion sites in peripheral blood from patients in the current trial as compared with those in previous trials revealed significantly less clustering of insertion sites within LMO2, MECOM, and other lymphoid proto-oncogenes in our patients.ConclusionsThis modified γ-retrovirus vector was found to retain efficacy in the treatment of SCID-X1. The long-term effect of this therapy on leukemogenesis remains unknown. (Funded by the National Institutes of Health and others; ClinicalTrials.gov numbers, NCT01410019, NCT01175239, and NCT01129544.)

Streptavidin suppresses T cell activation and inhibits IL-2 production and CD25 expression

Streptavidin is widely used as a detection tool in biology research because of its high affinity and specificity binding to biotin. Biotin–streptavidin system has also been explored for detection of infection and tumor in clinical medicine. Here, we show immunosuppressive property of streptavidin on T cell activation and proliferation. Upon CD3 and CD28 stimulation, CD4+ T cells produce interleukin 2 (IL-2) and express IL-2 receptor α chain (CD25). Addition of streptavidin in T cell culture suppressed IL-2 synthesis and CD25 expression with no cytotoxicity. The immunosuppressive effect of streptavidin was reversed by excessive biotin. Conjugated to a single chain anti-CD7 variable fragment (scFvCD7), streptavidin was directly delivered to T cells and showed substantially more profound suppressive effect on T cell activation. These results suggest that streptavidin could potentially be used as a novel immunomodulator.

Abstract LB-325: Antitumor effect of resveratrol combined with immunocytokine immunotherapy

Abstract Resveratrol (RV) is a natural compound which is currently being investigated for many possible health promoting activities. It has anti-tumor activity on cancer cells in vitro and in vivo in some animal models of cancer. We are currently examining the ability of RV to be combined with immunotherapy to treat cancer. Our immunotherapy is the hu14.18-IL2 immunocytokine (IC), consisting of the hu14.18 mAb (that targets GD2 on the surface of some tumor cells) linked to interleukin-2 (IL2). The IL2 component attracts and activates immune effector cells expressing IL2 receptors and induces localized destruction of the tumor via antibody dependent cell-mediated cytotoxicity (ADCC) by NK cells. Prior studies have found RV to be immunosuppressive in vitro but not in vivo. RV at a daily intragastric (i.g.) dose of 50mg/kg (1mg per mouse) slowed tumor growth in mice bearing neuroblastoma and was not immunosuppressive. At this dose the peak serum RV level was ∼ 1mcM. Using proliferative and cytotoxicity assays we were defining a dose in vitro and a regimen in vivo that does not suppress the immune system and is additive or synergistic in mediating anti-tumor effects when combined with immunotherapy. In our in vitro studies high concentrations of RV (≥ 25mcM) were found to inhibit both tumor cell proliferation and the ability of PHA and IL2 to stimulate proliferation of human and murine effector cells (measured by 3H-thymidine incorporation and by dilution of CFSE in daughter cells). These cells were arrested in their G1 phase. In addition, these high RV concentrations prevented effector cells from mediating ADCC in vitro. In contrast, 1mcM (as found in serum after i.g. treatment) was not tumoristatic or immunosuppressive in vitro. Systemic RV regimens, although inhibiting tumor growth in vivo, did not induce tumor regression in these models, probably because of the limited amount of RV reaching the tumor. In order to increase the amount of RV in the tumor, studies on the anti-tumor effect of peritumoral (p.t.) injections of 20mg RV in vivo in NXS2 neuroblastoma-bearing mice were performed. The results of these studies showed that peritumoral RV had a robust but transient anti-tumor effect. Primary subcutaneous tumors initially regressed; however, most mice then developed metastatic tumors, and in some cases re-growth of the primary tumor, after cessation of RV therapy. In order to circumvent tumor recurrence and metastasis, intravenous (i.v) immunotherapy was combined with the p.t. injections of 20mg RV. Peritumoral injection with resveratrol enhanced the subsequent efficacy of immunotherapy. Further, most mice receiving p.t. RV in combination with IC not only resolved their primary tumors, but also survived without development of metastatic tumors. Sixty-one % of the mice receiving the combined therapy showed no detectable tumors by day 100 compared to 15-13% of the mice in the RV-alone or the IC-alone groups, respectively (p=0.001 and p=0.0003). These studies indicate the potential for a combined regimen of RV and hu14.18-IL2. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-325.

A Phase II Trial of Denileukin Diftitox in Patients With Previously Treated Advanced Non-Small Cell Lung Cancer

Denileukin diftitox, a chimeric protein, uses the cytocidal properties of diphtheria toxin to cells expressing interleukin-2 receptors. The aim of this study was to evaluate the efficacy and safety of denileukin diftitox in the treatment of advanced relapsed nonsmall cell lung cancer (NSCLC). Multicenter phase II trial in patients with NSCLC with Eastern Cooperative Oncology Group PS 0-2, stage IIIB/IV at diagnosis, who had failed at least 1 previous chemotherapy regimen. Denileukin diftitox was infused at 18 microg/kg/d x 5 days, every 21 days for 6 cycles. For the 41 patients enrolled, the median age was 56 years (range, 21-80), 25 were men, and the median number of previous chemotherapy regimens was 2 (range, 1-5). The median number of treatment cycles was 2 (range, 1-6). By RECIST criteria, 18 (44%) had stable disease, 10 (24%) progressive disease, and 13 (32%) were not evaluable for response as they received less than 2 treatment cycles. The median time to disease progression was 1.8 months [range, 0.3-11.3; 95% confidence interval (CI) 1.3-2.6]. Median survival was 5.8 months (range, 0.3-33.6; 95% CI 3.4-11.4). The median follow-up time was 16.1 month. One death from myocarditis verified at autopsy was attributed to treatment. One grade 4 toxicity (vascular leak syndrome) was encountered, and 18 grade 3 toxicities, primarily gastro-intestinal, vascular leak syndrome, and constitutional symptoms. Denileukin diftitox at current dose schedule has limited activity in patients with previously treated NSCLC, manifested by disease control without impact on survival.

Leukemia induction after a single retroviral vector insertion in Evi1 or Prdm16

Insertional activation of cellular proto-oncogenes by replication-defective retroviral vectors can trigger clonal dominance and leukemogenesis in animal models and clinical trials. Here, we addressed the leukemogenic potential of vectors expressing interleukin-2 receptor common gamma-chain (IL2RG), the coding sequence required for correction of X-linked severe combined immunodeficiency. Similar to conventional gamma-retroviral vectors, self-inactivating (SIN) vectors with strong internal enhancers also triggered profound clonal imbalance, yet with a characteristic insertion preference for a window located downstream of the transcriptional start site. Controls including lentivirally transduced cells revealed that ectopic IL2RG expression was not sufficient to trigger leukemia. After serial bone marrow transplantation involving 106 C57Bl6/J mice monitored for up to 18 months, we observed leukemic progression of six distinct clones harboring gamma-retroviral long terminal repeat (LTR) or SIN vector insertions in Evi1 or Prdm16, two functionally related genes. Three leukemic clones had single vector integrations, and identical clones manifested with a remarkably similar latency and phenotype in independent recipients. We conclude that upregulation of Evi1 or Prdm16 was sufficient to initiate a leukemogenic cascade with consistent intrinsic dynamics. Our study also shows that insertional mutagenesis is required for leukemia induction by IL2RG vectors, a risk to be addressed by improved vector design.

Activation of mitogen-activated protein kinase kinase (MEK)/extracellular signal–regulated kinase (ERK) signaling pathway is involved in myeloid lineage commitment

AbstractCommon lymphoid progenitors (CLPs) are lymphoid-lineage-committed progenitor cells. However, they maintain a latent myeloid differentiation potential that can be initiated by stimulation with interleukin-2 (IL-2) via ectopically expressed IL-2 receptors. Although CLPs express IL-7 receptors, which share the common γ chain with IL-2 receptors, IL-7 cannot initiate lineage conversion in CLPs. In this study, we demonstrate that the critical signals for initiating lineage conversion in CLPs are delivered via IL-2 receptor β (IL-2Rβ) intracellular domains. Fusion of the A region of the IL-2Rβ cytoplasmic tail to IL-7Rα enables IL-7 to initiate myeloid differentiation in CLPs. We found that Shc, which associates with the A region, mediates lineage conversion signals through the mitogen activated protein kinase (MAPK) pathway. Because mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) inhibitors completely blocked IL-2-mediated lineage conversion, MAPK activation, specifically via the MEK/ERK pathway, is critically involved in the initiation of this event. Furthermore, formation of granulocyte/macrophage (GM) colonies by hematopoietic stem cells, but not by common myeloid progenitors (CMPs), was severely reduced in the presence of MEK/ERK inhibitors. These results demonstrate that activation of MEK/ERK plays an important role in GM lineage commitment.

Cytomodulation of interleukin-2 effect by L-2-oxothiazolidine-4-carboxylate on human malignant melanoma.

Glutathione (GSH), the most prevalent intracellular non-protein thiol, plays an important role in the interleukin-2 (IL-2)-induced proliferative activity of normal and tumour cells expressing IL-2 receptor (IL-2R). In the present study, we investigate the effect of IL-2 on proliferation of the human melanoma A375 cell line, and the possible selective cytomodulation effect of this cytokine by L-2-oxothiazolidine-4-carboxylate (OTZ) on these melanoma cells and on human peripheral blood mononuclear cells (PBMCs). We found that recombinant IL-2 (rIL-2) significantly increased the proliferation rate of A375 melanoma cells, which was associated with an increase in GSH levels, the enhancement of IL-2Ralpha expression and the endogenous production of IL-2 in these tumour cells. In contrast, OTZ decreased GSH content and the proliferation rate of A375 cells, and abrogated the growth-promoting effects of rIL-2. Thus, compared to cells treated with rIL-2, pre-treatment with OTZ reduced IL-2Ralpha expression, and also decreased the consumption of rIL-2 and the endogenous secretion of IL-2 by these tumour cells. With regard to PBMCs, the combination of OTZ plus rIL-2 resulted in a more rapid and greater increase of IL-2Ralpha expression than rIL-2 alone, with the proliferation rate being similar in the first 24 h, but with a lower PBMC' count found thereafter compared to rIL-2 treatment alone. These results suggest that OTZ plays a crucial role in obtaining a selective cytomodulation of rIL-2, enabling it to exert its growth-promoting effect on normal cells, but not on melanoma cells, thereby possibly improving biochemotherapy with rIL-2.

Effects of Increased Dietary Protein and Energy on Composition and Functional Capacities of Blood Mononuclear Cells from Vaccinated, Neonatal Calves

Effects of increased protein and energy provided by an intensified milk replacer on the antigen-specific, cell-mediated immune response of the neonatal calf were examined. Calves were fed a standard (0.45 kg/day of a 20% crude protein, 20% fat milk replacer; n=11) or intensified (1.14 kg/day of a 28% crude protein, 20% fat milk replacer; n=11) diet from 0 to 6 weeks of age. All calves were vaccinated with Mycobacterium bovis bacillus Calmette-Guerin (BCG) at 1 week of age. The daily weight gain of intensified-diet calves (0.62 kg/day) was greater than the weight gain of standard-diet calves (0.29 kg/day). Liver, kidney, heart, thymus, and subcervical lymph nodes from intensified-diet calves were heavier than the same organs from standard-diet calves. Flow cytometric analysis of peripheral blood mononuclear cell (PBMC) populations indicated that CD4+ cells, gamma delta TCR+ cells, and monocyte percentages, although unaffected by diet during the first 5 weeks of the study, were higher in intensified-diet calves at week 6. The decline in gamma delta TCR+ cell percentages and increase in B cell percentages with increasing age seen in all calves are characteristic of the maturing immune system of the calf. CD8+ T cell or B cell percentages were not affected by diet. In intensified-diet calves, percentages of CD4+ expressing interleukin-2 receptor increased and percentages of gamma delta TCR+ cells expressing interleukin-2 receptor decreased with time. The same populations in standard-diet calves did not change with time. Percentages of CD4+ and CD8+ T cells, and B cells expressing MHC class II antigen, were unaffected by diet or age. Although mitogen-induced interferon (IFN)-gamma and nitric oxide (NO) secretion increased with age for all calves, PBMC from intensified-diet calves produced less IFN-gamma and more NO than did cells from standard-diet calves at week 6 of the study. Antigen-induced secretion of IFN-gamma and NO also increased with age but was unaffected by diet. Antigen-elicited delayed-type hypersensitivity was unaffected by diet, suggesting increased dietary protein and energy did not alter adaptive immunity in vivo. Overall, these results suggest that feeding calves a commercially available, intensified milk replacer affects minimally the composition and functional capacities of PBMC populations. Additional research is necessary to determine whether these subtle effects influence the calf's susceptibility to infectious disease.

Overexpression of interleukin‐2 receptor α in a human squamous cell carcinoma of the head and neck cell line is associated with increased proliferation, drug resistance, and transforming ability

It has been previously demonstrated that human carcinomas express interleukin-2 receptor (IL-2R) alpha, beta, and gamma chains. The beta and gamma chains of IL-2R have intermediate binding affinity for IL-2 and are responsible for the intracellular signaling cascades after IL-2 stimulation. IL-2Ralpha lacks the cytoplasmic domain, but is essential for increasing the IL-2-binding affinity of other receptors. Overexpression of IL-2Ralpha in tumor cells is associated with tumor progression and a poor patient prognosis. To define molecular mechanisms responsible for the effects associated with IL-2Ralpha expression, ex vivo experiments were performed with the squamous cell carcinoma head-and-neck cancer line, PCI-13, which was genetically engineered to overexpress the IL-2Ralpha chain. While IL-2Ralpha-overexpressing PCI-13 cells were capable of forming colonies in soft agar, PCI-13 cells transfected with the control vector or those expressing IL-2Rgamma did not. Consistently, IL-2Ralpha-expressing tumor cells proliferated more rapidly than the control or IL-2Rgamma+ cells, associated with increased levels of cyclins A and D1 and cyclin-dependent kinase (cdk(s)) 2 and 4 proteins. In addition, IL-2Ralpha-expressing cells were significantly more resistant to apoptosis induction by a tripeptidyl proteasome inhibitor (ALLN) and two chemotherapeutic drugs (VP-16 and taxol) than the control or IL-2Rgamma+ cells. Accompanying the drug resistance, high levels of anti-apoptotic Bcl-X(L) and Bcl-2 proteins were found in the mitochondria-containing fraction of IL-2Ralpha-expressing tumor cells. Treatment of IL-2Ralpha-expressing cells with a specific Janus kinase 3 (Jak3) inhibitor decreased expression of cyclin A, cyclin D1, Bcl-X(L), and Bcl-2 proteins. Finally, high levels of ubiquitinated proteins were detected in the proliferating IL-2Ralpha-expressing cells. Our data suggest that increased proliferation rates and decreased drug sensitivity of IL-2Ralpha-expressing tumor cells are responsible for the enhanced tumor aggressiveness and poor clinical prognosis of patients whose tumors express IL-2Ralpha.

Effect of interleukin-2 and selenium on the growth of squamous cell carcinoma cells

Objectives: The objectives of this study were to determine whether the expression of the interleukin-2 (IL-2) receptors on squamous cell carcinoma cells can be enhanced in the presence of selenium (Se) and contribute to a greater retardation of tumor growth after locoregional therapy with IL-2. Study design: The growth of the cells was studied after in vitro or dietary supplementation with Se in a murine model. Results: Treatment of established tumors in hosts supplemented with Se with peritumoral injections of IL-2 resulted in 50% reduction of tumor size, whereas treatment of early tumors resulted in 72.4% reduction. The effect was most likely related to a combination of enhanced immune responsiveness and enhanced IL-2 receptor expression on the tumor cells. Conclusions and significance: The data suggested that local immunotherapy with IL-2 in hosts supplemented with Se may represent an effective modality of treatment for the prevention of recurrences at the site of conventionally treated primary tumors, including tumors that do not express IL-2 receptors.

Cytokine serum levels, autologous mixed lymphocyte reaction and surface marker analysis in never medicated and chronically medicated schizophrenic patients

A number of immunological parameters were studied in 82 DSM-III-R diagnosed schizophrenic patients (53 first drug-naive and 29 medicated chronic patients) as well as 62 healthy blood donors. The serum levels of interleukin-2 (IL-2), interleukin-1 beta (IL-1β) and tumour necrosis factor-alpha (TNF-α) were measured and correlated with cellular immunity, as assessed by the autologous mixed lymphocyte reaction (AMLR). T lymphocyte subsets were also examined. The above immune parameters were reassessed in a subgroup of 11 first-episode, drug-naive patients 1 month after neuroleptic medication. IL-2 serum levels were significantly lower, and IL-1β and TNF-α were significantly higher in schizophrenic patients compared with healthy donors ( P<0.001); no significant difference was observed between the two patient groups (medicated and not medicated). Abnormal cytokine serum levels were associated with decreased AMLR responses in vitro. Increased percentages of activated CD4+ and CD16+ natural killer cells, as well as cells expressing ICAM-1 adhesion molecules and IL-2 specific receptors, were detected in the patients. Immunophenotype studies revealed a higher percentage of cells expressing IL-2 receptors in medicated chronic schizophrenic patients compared with drug-naive patients. The abnormal cytokine production in vivo, along with the low AMLR responses in vitro, and the high percentage of activated CD4+ lymphocytes presented in this study suggest alterations in the immune system of schizophrenic patients (medicated or not medicated) consistent with immune activation.

BIOPHARMACEUTICS OF LIPOSOMAL INTERLEUKIN 2, ONCOLIPIN

Oncolipin is a multilamellar liposomal (dimyristoyl phosphatidylcholine) formulation of interleukin 2 (IL-2) and human serum albumin (HSA) with distinct surface characteristics which may influence its biological activities. IL-2 and HSA were detected on the surface of the liposomes using specific antibody staining. Surface expression of IL-2 was also demonstrated by the observation that Oncolipin bound to cells expressing IL-2 receptors (IL-2R) containing αβγ or βγ subunits. Binding and internalization of Oncolipin by cells expressing αβγ or βγ receptor subunits was blocked by excess free IL-2 or a neutralizing antibody against the β chain. The display of surface IL-2 on Oncolipin's liposomes was maintained in vivo after intravenous injection into mice. IL-2 was also present between the lipid bilayers of the multilamellar liposomes based on the unique physical characteristics detected by freeze fracture electron microscopy. The bulk of the liposome-associated IL-2 was released from the liposomes upon incubation at 37°C in medium containing serum, indicating that the IL-2 was not irreversibly entrapped on or in the liposome structure. Thus, Oncolipin is receptor-targeted to activated T and NK cells by virtue of its surface expression of IL-2 and has the potential to release IL-2 following deposition within lymphoid organs. These properties may confer distinct advantages over soluble IL-2 for immunotherapy of cancer and viral diseases.

Immune response in chronic periapical parodonititis.

The purpose of our study was to investigate the immune response in chronical periapical parodontitis (CPP) by using multidisciplinary approach. 30 CPP samples were obtained after surgical removal - apicoectomy. Each CPP sample was examined by histological, bacteriological and flow cytometrical (FC) analysis of lymphocytes infiltrating CPP samples. Ten percent of bacteriological samples were sterile, others had significant aerobic and anaerobic growth. We used patohistologic and microbiologic findings and compare them to the results of imunological analysis. By FC we found a significant increase in proportions of T lymphocytes expressing interleukin-2 receptors and ICAM-1 compared to peripheral blood lymphocytes. Proportions of T helper cells that produce interferon-gama (IFN-gamma) was higher in CPP samples predominantly colonized by anaerobic bacteria. There were no differences in IL-4 expression by T cells in both groups (anaerobic and streptoccoccal). Among anaerobic CPP samples differences in proportion of T cells that express IL-2 receptors expression was also found between samples colonised by P. acnes and Bacteroides sp. Oral streptococci cause relatively limited tissue destruction and induce Th2 type of immune response accompanied by non-cytotoxic inflammatory reaction. On the contrary, anaerobic bacteria induce Th1 type of immune response that cause more severe inflammatory reaction (type 4 of hypersensitivity that damage the tissue by the action of cytotoxic T cell activation.

Efficacy of repeated cycles of chemo-immunotherapy with thymosin alpha1 and interleukin-2 after intraperitoneal 5-fluorouracil delivery.

We have used chemo-immunotherapy with 5-fluorouracil (5-FU), thymosin alpha1 (T alpha1) and interleukin-2 (IL-2) to treat multiple liver metastases from colorectal cancer induced by DHD/K12 cells in syngeneic BDIX rats, comparing one and two cycles of treatment, and different treatment combinations. 5-FU was delivered loco-regionally as a continuous infusion via an intraperitoneal (i.p.) catheter from a subcutaneously implanted mini-pump, a method we developed for this study. We show here that two cycles of a triple chemo-immunotherapy regimen significantly increased the average survival time compared to one cycle, and compared to untreated controls or those treated with two cycles of 5-FU alone. At 150 days, two rats treated with two cycles of triple therapy were cured, showing no signs of cancer at autopsy; all the other rats died before this time. Triple chemo-immunotherapy resulted in significantly fewer extra-hepatic metastases than in the controls and in those treated with 5-FU only. Further, we found that two cycles of triple treatment significantly increased the absolute number of peripheral T cells expressing IL-2 receptor, CD4 and CD8 compared to controls. We conclude that two cycles of chemo-immunotherapy with 5-FU, T alpha1 and IL-2 were superior to one cycle of treatment and to other treatments tested. Our results suggest that the triple therapy acts by increasing numbers of effector T cells. This method shows promise for the use of multi-cycle chemo-immunotherapy in the treatment of unresectable metastases of colorectal cancer in humans.

Human Peripheral Blood Mononuclear Cells Express Gonadotropin-Releasing Hormone (GnRH), GnRH Receptor, and Interleukin-2 Receptor -Chain Messenger Ribonucleic Acids That Are Regulated by GnRH in Vitro

Human Peripheral Blood Mononuclear Cells Express Gonadotropin-Releasing Hormone (GnRH), GnRH Receptor, and Interleukin-2 Receptor -Chain Messenger Ribonucleic Acids That Are Regulated by GnRH in Vitro

Human peripheral blood mononuclear cells express gonadotropin-releasing hormone (GnRH), GnRH receptor, and interleukin-2 receptor gamma-chain messenger ribonucleic acids that are regulated by GnRH in vitro.

The hypothalamic decapeptide, GnRH, plays a critical role in human reproduction. In addition to the well known effects of GnRH on pituitary cells, there is evidence supporting the presence of GnRH-binding sites in tissues other than pituitary cells, including lymphocytes. In addition, a GnRH-like substance has been found to be secreted from lymphoid cells. However, the precise nature of GnRH secretion and binding in immune cells has not been fully established. In this study, we used the RT-PCR method to examine the expression and regulation of GnRH, GnRH receptor (GnRHR), and interleukin-2 receptor gamma-chain messenger ribonucleic acids (mRNAs) in human peripheral blood mononuclear cells. It was found that human mononuclear cells expressed GnRH and GnRHR mRNAs. Nucleotide sequences of these mRNAs are identical to their hypothalamic and pituitary counterparts, respectively. In addition, GnRH and GnRHR mRNA expressions in peripheral blood mononuclear cells are regulated by GnRH and its synthetic analogs in vitro. Treatment with various concentrations of GnRH (10(-5)-10(-11) mol/L) increased GnRHR mRNA expression in a dose-dependent manner (maximal level is 158% of the untreated control value at 10(-8) mol/L GnRH; P < 0.05), but reduced GnRH mRNA levels to 69% of the untreated control value at 10(-9) mol/L GnRH (P < 0.05). Cotreatment of GnRH with a GnRH antagonist blocked these regulatory effects, indicating the receptor-mediated nature of the GnRH action. Both GnRH and GnRH agonist stimulated interleukin-2 receptor gamma-chain mRNA in a dose-dependent manner, indicating that GnRH may be involved in lymphocyte activation. In summary, these observations suggest that mRNAs encoding the pituitary form of GnRHR and the hypothalamic form of GnRH are also expressed in human peripheral blood mononuclear cells. The endogenous production of GnRH by lymphocytes may act as an autocrine or paracrine factor to regulate immune functions. Because of the presence of GnRHR on lymphocytes, exogenous GnRH analog therapy may have an impact on the immune system through these receptors.

Monitoring soluble interleukin-2 receptor levels in related and unrelated donor allogenic bone marrow transplantation.

Acute graft-versus-host disease (GVHD) is effected by donor T lymphocytes which have been stimulated by host antigens. Activated donor T lymphocytes express interleukin-2 receptor (IL-2R), which is comprised of three subunits (alpha, beta, gamma). During activation, the a IL-2R subunit (CD25) is shed from the receptor complex and can be measured in the circulation. Soluble IL-2Ralpha (sIL-2R) levels are increased in states of immune activation including GVHD, and could theoretically be used as a guide to therapy. Since IL-2Ralpha expression is an early marker of T cell activation, we investigated: (1) if an increase in sIL-2R is specific for acute GVHD; and (2) if serial sIL-2R levels can identify patients with early GVHD, prior to the onset of clinical tissue damage (effector function). Weekly sIL-2R levels were monitored in 36 patients undergoing matched related (n=23) or matched unrelated (n=13) allogeneic bone marrow transplantation (BMT). There was no significant difference in sIL-2R levels between matched related and matched unrelated recipients. Patients with acute GVHD (n=19, 53%) demonstrated higher sIL-2R levels, than those without during weeks 2 and 3 post-BMT (P=0.02 and 0.04, Mann-Whitney U test, two-tailed). In patients with acute GVHD, the rise in sIL-2R preceded the clinical signs of GVHD (16/19 patients). However, patients with sepsis demonstrated a trend towards higher sIL-2R levels at week 1 and significantly greater levels by week 4 (P=0.02). Furthermore, patients with veno-occlusive disease (VOD) (25%) also had significantly higher sIL-2R levels at week 2 (P=0.03). We conclude that although sIL-2R levels increase in patients with acute GVHD, similar increases are seen in patients with VOD and/or sepsis and therefore, as a single biochemical marker, we find that serial measurements of sIL-2R lacks sufficient specificity to guide GVHD therapy.

Microtubule depolymerization inhibits clathrin coated-pit internalization in non-adherent cell lines while interleukin 2 endocytosis is not affected.

The microtubule cytoskeleton is generally not considered to be essential for the first steps of clathrin-mediated endocytosis of membrane receptors. Its role in clathrin-independent endocytosis has not been investigated. We have previously shown that the cytokine interleukin 2 (IL2) is internalized in lymphoid cells expressing its receptors when clathrin-dependent endocytosis is inhibited. Here we compare the internalization of IL2 and of transferrin, a marker of clathrin-dependent endocytosis, after microtubule disruption. In hemopoietic cell lines, which express IL2 receptors, transferrin receptor entry was inhibited by about 40%. However, in adherent cell lines, transferrin entry was unaffected by microtubule disruption, as previously reported. Unlike the case for transferrin, internalization of IL2 receptors was not affected by depolymerization of the microtubule cytoskeleton in hemopoietic cell lines. These results show that IL2 and transferrin receptors do not have the same endocytic properties and support our previous conclusion that these receptors follow different pathways of endocytosis.