Recombinant interleukin-2 directly augments the cytotoxicity of human monocytes

Pregnancy Zone Protein (PZP) is significantly upregulated in the decidua of recurrent and spontaneous miscarriage and negatively correlated to Glycodelin A (GdA)

BACKGROUND

Pregnancy Zone Protein (PZP) is an immunosuppressive protein that is expressed by the placenta and has also been identified in immune cells. When PZP and Glycodelin A (GdA) are combined, they act synergistically to inhibit Th-1 immune response. Little is known about its combined expression and role in normal and disturbed first trimester pregnancy.

PATIENTS AND METHODS

We investigated the expression of PZP and GdA in placental tissue obtained from spontaneous miscarriage (SM) (n = 19) and recurrent miscarriage (RM) (n = 17) at gestational weeks 6-13 by immunohistochemistry and on mRNA-level by either TaqMan PCR or in situ hybridization. Placental tissue from legal terminations of healthy pregnancies (n = 15) served as control group. Immunofluorescence double staining was used to analyse the combined expression of PZP and GdA in decidual tissue.

RESULTS

The protein level of PZP was significantly increased in decidual stroma of SM samples compared to the decidua of control specimens and also significantly upregulated in the decidual stroma cells in the RM group. Concerning GdA, the decidual stroma revealed a significantly decreased protein level in the group with spontaneous abortions than in the group with healthy pregnancies. There was also a significant downregulation of GdA in the decidual stroma of RM samples compared to the control group. We observed a significant negative correlation of PZP and GdA in decidual stromal tissue of recurrent abortion. We could confirm the staining results for PZP as well as for GdA on mRNA level. Both proteins are co-localized in decidual stroma as analysed by immunofluorescence double staining.

CONCLUSION

A balanced expression of GdA and its carrier protein PZP in the decidua seems crucial for a successful ongoing pregnancy. According to our data, these immunosuppressive proteins are co-localized in the decidual tissue and show a negative correlation only in patients suffering from recurrent abortion.

Infectivity and viability of dengue virus infected hepatocytes cocultured with peripheral blood mononuclear cells from a healthy subject

BACKGROUND Dengue virus (DENV) can infect and replicate in monocytes, resulting in antibody-dependent enhancement. The liver is the main target of DENV, and the infection mechanisms of DENV include direct cytopathic effects (CPEs) of the virus, mitochondrial dysfunction, and effect of cellular and humoral immune factors in the liver. This study was aimed to explore the infectivity of DENV and viability of human hepatocytes using Huh 7it-1 cells cocultured with peripheral blood mononuclear cells (PBMCs). METHODS Huh 7it-1 cells were infected with dengue virus serotype-2 (DENV-2) New Guinea C strain at multiplicity of infection of 0.5 and 1 FFU/cell, and cocultured in vitro with and without adherent PBMCs. The infectivity of DENV was assessed by immunoperoxidase staining. The viability of Huh 7it-1 cells was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT, a tetrazole) assay and trypan blue staining. Data were statistically analyzed by Shapiro–Wilk and analysis of variance for normality significances. RESULTS The result showed that addition of PBMCs to DENV-2 infected Huh 7it-1 cells decreased the infectivity of DENV (15–37%). DENV-2 infection decreased the viability of Huh 7it-1 cells (15.5–20.8%). Despite the decrease in infectivity of DENV, the addition of PBMCs increased the Huh 7it-1 cells viability (4.5–10.2%). CONCLUSIONS Addition of PBMCs to Huh 7it-1 cells that are infected with DENV-2 decreased the infectivity of DENV and increased Huh 7it-1 cells viability.

In Which Patients with Sarcoidosis Is FDG PET/CT Indicated?

Sarcoidosis is a granulomatous disease of which the etiology remains unknown. The diverse clinical manifestations may challenge clinicians, particularly when conventional markers are inconclusive. From various studies, it has become clear that fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT aids in sarcoidosis care. In this article, an update on FDG PET/CT in sarcoidosis is provided. The use of FDG PET/CT in the diagnostic process of sarcoidosis is explained, especially in determining treatable inflammatory lesions in symptomatic patients with indecisive conventional tests. Furthermore, FDG PET/CT for evaluating the potential benefit of additional inflammatory treatment is described and its use in cardiac sarcoidosis is highlighted.

A Phase I Study of Recombinant Interleukin 2 in Melanoma Patients. Toxicity and Clinical Effects

Toxicity and clinical effects of a new brand of recombinant interleukin 2 (rIL2, Bioleukin™, Biogen, Geneva) were evaluated by a phase I study in 12 patients with stage III melanoma. Escalating doses from 100 μg/m2 to 800 μg/m2 were administered thrice a day with bolus injections given via a peripheral venous catheter for up to a maximum of 7 days. All patients showed malaise, fever and chills and mild gastrointestinal side effects. A modest electrolyte imbalance (hypocalcemia and hypokalemia) was detected in all 12 patients. Renal toxicity as judged by serum creatinine was not observed, and hepatic toxicity was moderate with the possible exception of one patient who had an unclear previous history of liver dysfunction. Mild, transient leukopenia was found in several patients, whereas thrombocytopenia developed in 4 patients; no anemia was observed. Cutaneous rash was seen in half of the patients treated. Fluid retention was minimal, with a weight gain associated to treatment that never exceeded 10% of pretreatment body weight. Electrocardiographic alterations developed in 2 patients in the form of ventricular and supraventricular extrasystoles. In 2 patients given the highest dose of rIL2, a significant reduction in transfer lung factor for carbon monoxide was seen, indicating alterations in pulmonary functions. Other dose-related toxicities were thrombocytopenia and malaise. All side effects disappeared 2-3 days after the end of rIL2 administration. No major responses were seen in association with the 4-8 days of treatment given in this study.

Nonmuscle invasive bladder cancer: a primer on immunotherapy

Intravesical Bacillus Calmette-Guérin (BCG) has long been the gold standard treatment of nonmuscle invasive bladder cancer. Recently, there has been an emergence of novel immunotherapeutic agents, which have shown promise in the treatment of urothelial cell carcinoma. These agents aim to augment, modify, or enhance the immune response. Such strategies include recombinant BCG, monoclonal antibodies, vaccines, gene therapy, and adoptive T-cell therapy. Here, we review the emerging immunotherapeutics in the treatment of nonmuscle invasive bladder cancer.

Novel immunotherapeutic approaches to the treatment of urothelial carcinoma

Immunotherapy has long played a role in urothelial cancers with the use of bacille Calmette Guérin (BCG) being a mainstay in the treatment of nonmuscle invasive bladder cancer. Novel therapeutic approaches have not significantly impacted mortality in this population and so a renaissance in immunotherapy has resulted. This includes recombinant BCG, oncolytic viruses, monoclonal antibodies, vaccines, and adoptive T-cell therapy. Herein, we provide a review of the current state of the art and future therapies regarding immunotherapeutic strategies for urothelial carcinoma.

Fusion cytokine IL-2-GMCSF enhances anticancer immune responses through promoting cell-cell interactions

Background

Potent antitumor responses can be induced through cytokine immunotherapy. Interleukin (IL)-2 and granulocyte–macrophage colony-stimulating factor (GM-CSF) are among the most effective cytokines to induce tumor-specific systemic immune responses and can act synergistically. To overcome the limitations of combined use of these two cytokines, we have constructed an IL2-GMCSF fusion protein and characterized its antitumor effects in this study.

Methods

The expression of IL-2 receptor and GM-CSF receptor of cell lines were detected with quantitative real-time PCR. On this basis, the bioactivities of IL2-GMCSF, especially effects on DC2.4 cells were assayed. Another function of IL2-GMCSF—bridge two types of cells—was assessed by cell contact counting and cytotoxicity assays. The anti-tumor activity in vivo of IL2-GMCSF was evaluated in the melanoma model. The statistical significance among treatment groups were determined by One-Way ANOVA.

Results

The fusion protein IL2-GMCSF maintained the activities of IL-2 and GM-CSF, and could significantly promote DC2.4 cell activities, including phagocytosis, proliferation and cytokine secretion. In addition to the inherent cytokine activity, IL2-GMCSF bridges direct cell–cell interactions and enhances splenocyte killing efficacy against multiple tumor cell lines in vitro. Co-injection of IL2-GMCSF and inactivated B16F10 mouse melanoma cells induced complete immunoprotective responses in about 30 % of mice.

Conclusion

These results suggested that IL2-GMCSF can efficiently regulate immune responses against tumors. Furthermore, as the bridging effect relies on both IL-2R and GM-CSFR and promotes interactions between immune and tumor cells, IL2-GMCSF may be utilized as a useful tool for dissecting specific immune responses for future clinical applications.

Recombinant bacillus Calmette-Guérin in urothelial bladder cancer immunotherapy: current strategies

Bacillus Calmette-Guérin (BCG) has been used in the intravesical treatment of urothelial bladder cancer (UBC) for three decades. Despite its efficacy, intravesical BCG therapy is associated with some limitations such as side effects and BCG failure, which have inspired multiple ways to improve it. Recent advances have focused on recombinant BCG (rBCG) which provides a novel tactic for modification of BCG. To date, a number of rBCG strains have been developed and demonstrated to encourage efficacy and safety in preclinical and clinical studies. This review summarizes current rBCG strategies, concerns and future directions in UBC immunotherapy with an intention to encourage further research and eventually to inform clinical decisions.

Suppression of monocyte and neutrophil function by recombinant IL-2

Little IS known about the influence of IL-2 on phagocytes. We now describe the effects of human recombinant IL-2 on human neutrophil and monocyte functions related to mobility, phagocytosis, glucose uptake, respiration and degranulation. Neutrophil adherence and hexose monophosphate shunt activities were both suppressed after incubation with IL-2. IL-2 had no effect on neutrophil migration, phagocytosis, deoxyglucose uptake or degranulation, ionocytes demonstrated a greater sensitivity to IL-2 with suppression of monocyte adherence, random and stimulated migration, glucose uptake and hexose monophosphate shunt activity, even after addition of phorbol myristate acetate. Monocyte phagocytosis and degranulation were not affected. All of the effects observed were dose-dependent within a biologically active range for IL-2. These studies suggest that IL-2 may have an important down-regulatory role across a broad range of monocyte functions including movement, deoxyglucose uptake and respiration. However, its role in regulation of neutrophil function is limited to adherence and respiration. IL-2 may be a more versatile cytokine than has previously been appreciated.

Bladder Cancer Immunotherapy: BCG and Beyond

Mycobacterium bovis bacillus Calmette-Guérin (BCG) has become the predominant conservative treatment for nonmuscle invasive bladder cancer. Its mechanism of action continues to be defined but has been shown to involve a T helper type 1 (Th1) immunomodulatory response. While BCG treatment is the current standard of care, a significant proportion of patients fails or do not tolerate treatment. Therefore, many efforts have been made to identify other intravesical and immunomodulating therapeutics to use alone or in conjunction with BCG. This paper reviews the progress of basic science and clinical experience with several immunotherapeutic agents including IFN-α, IL-2, IL-12, and IL-10.

Biologic and clinical significance of cytokine production in B-cell malignancies

Cytokines are a group of polypeptide hormones endowed with pleiotropic biological properties. Normal B lymphocytes produce a number of these factors that subserve important regulatory functions in the combined processes of proliferation and differentiation. Also neoplastic B cells can release cytokines and, simultaneously, respond to the same factors in an autocrine circuit that supports their malignant growth. In addition, tumor cells can make use of the factors released by normal cells, either spontaneously or under the influence of inductive signals from the neoplastic cells. Inappropriate or excessive release of cytokines may have an important role in the pathophysiology of some clinical features. Thus, neutralization of cytokine biologic activity in vivo could be a therapeutic strategy for treatment of human B-cell neoplasias.

Peripheral blood mononuclear cells increase the permeability of dengue virus-infected endothelial cells in association with downregulation of vascular endothelial cadherin

Plasma leakage is one of the characteristic features of dengue haemorrhagic fever. The interaction among peripheral blood mononuclear cells (PBMCs), dengue virus and endothelial cells was analysed in vitro. Human umbilical vein endothelial cells (HUVECs) were infected with dengue-2 virus (DV-2) at an m.o.i. of 0.5 p.f.u. per cell. PBMCs were added to DV-2-infected HUVECs, and transendothelial electrical resistance (TEER) and transalbumin permeability were assessed. Dengue virus infection at an m.o.i. of 0.5 p.f.u. per cell alone did not decrease the TEER, but addition of PBMCs decreased the TEER, increased the albumin permeability and induced morphological changes of HUVECs. The extent of the decrease was more profound with adherent PBMCs than with non-adherent PBMCs. The expression of vascular endothelial cadherin (VE-cadherin) was examined using real-time RT-PCR and immunofluorescence. Addition of PBMCs to DV-2-infected HUVECs decreased the levels of mRNA transcripts and cell-surface expression of VE-cadherin. The results indicate that PBMCs increased the permeability of DV-2-infected HUVECs and that the increased permeability was concomitant with morphological change and the decrease in VE-cadherin expression. The results suggest that functional impairment of the DV-2-infected HUVEC monolayer was caused by interaction with PBMCs.

T cells contribute to lysophosphatidylcholine-induced macrophage activation and demyelination in the CNS

We have previously shown that intraspinal microinjection of lysophosphatidylcholine (LPC), a potent demyelinating agent, results in a rapid but brief influx of T cells (between 6 and 12 h). This is accompanied by a robust activation of macrophages/microglia that leads to demyelination by 48 h. In the present study, we examined whether this brief influx of T cells contributes to the activation of macrophages/microglia and demyelination by injecting LPC into the dorsal column white matter of athymic Nude mice that lack T cells. We show that there is a significant reduction in macrophage/microglial activation and myelin clearance after LPC injection in Nude mice as compared with wildtype controls. We also show that there is no difference in the recruitment of hematogenous macrophages into the spinal cord after LPC injection in the two mouse strains. Of the T cell cytokines assessed, there was a marked reduction in the mRNA expression of interleukin-2 (IL-2) in Nude mice compared with wildtype animals. Neutralizing IL-2 with function-blocking antibodies in wildtype animals resulted in a significant decrease in the number of phagocytic macrophages/microglia and a reduction in demyelination induced by LPC. While there may be other defects in Nude mice that might contribute to the effects shown here, these data suggest that the brief influx of T cells in this model of chemically-induced demyelination could play a role in macrophage/microglial activation and demyelination. These results may also have implications for remyelination in this and other types of CNS damage.

Recombinant bovine interleukin 2 enhances immunity and protection induced by Brucella abortus vaccines in cattle

Augmentation of immunization of cattle Brucella abortus S19 or a B. abortus soluble protein extract (SPEBA) vaccine through administration of recombinant bovine IL 2 (rBoIL 2) was evaluated. Seventy-five heifers were divided among 6 groups that were treated with the following: Group 1, no treatment; Group 2, rBoIL 2 (1microg/kg) on day 0; Group 3, SPEBA (2 mg) on day 0 and week 9; Group 4, SPEBA + rBoIL 2 on day 0, SPEBA on week 9; Group 5, S19 (10(7) CFU) on day 0 and week 9; Group 6, S19 + rBoIL 2 on day 0, S19 only on week 9. Approximately, 6 months after vaccination, cattle were bred by natural service, and at mid-gestation pregnant cattle were challenged intraconjunctivally with 9.1 x 10(5) CFU of virulent B. abortus S2308. Pre- and post-challenge antibody responses were measured by an enzyme-linked immunosorbent assay, a particle concentration fluorescence assay, and the card test. Lymphoproliferation (LP) responses to gamma-irradiated B. abortus and SPEBA antigens were measured in peripheral blood mononuclear cells. After vaccination, antibody responses to B. abortus elevated rapidly in SPEBA- and S19-vaccinates with and without rBoIL 2, however, these responses were significantly (P < 0.05) higher in vaccinates which also received rBoIL 2. Antibody levels for all vaccinated groups had returned to those of negative control groups by the challenge date with the exception of the SPEBA/rBoIL 2 group. In general, LP responses were higher in vaccinated or rBoIL 2-treated cattle than for unvaccinated controls. Challenge of 48 pregnant heifers resulted in abortions in 4/9 of Group 1, 0/9 of Group 2, 4/8 of Group 3, 2/9 of Group 4, 1/7 of Group 5, and 0/6 of Group 6 cattle. Treatment with rBoIL 2 alone (Group 2) provided significant (P < 0.05) protection from infection, abortions and induction of sero-positive status compared to untreated (Group 1) cattle. Co-administration of rBoIL 2 with S19 resulted in significant (P < 0.05) augmentation in onset, duration and magnitude of LP responses to B. abortus antigens following challenge. Characterization of the cytokine response of bovine monocyte-derived macrophages by real-time polymerase chain reaction indicated that in vitro stimulation of these cells with rBoIL 2 resulted in a profound up-regulation of genes encoding tumor necrosis factor-alpha, IL 12p40, and interferon-gamma reflecting activation of the cells. Overall, rBoIL 2-treatment was associated with fewer infections, sero-conversions and a significant (P = 0.02) level of protection against abortion as compared to vaccination alone or no treatment.

The immunoregulatory and allergy-associated cytokines in the aetiology of the otitis media with effusion

Inflammation in the middle ear mucosa, which can be provoked by different primary factors such as bacterial and viral infection, local allergic reactions and reflux, is the crucial event in the pathogenesis of otitis media with effusion (OME). Unresolved acute inflammatory responses or defective immunoregulation of middle inflammation can promote chronic inflammatory processes and stimulate the chronic condition of OME. Cytokines are the central molecular regulators of middle ear inflammation and can switch the acute phase of inflammation in the chronic stage and induce molecular-pathological processes leading to the histopathological changes accompanying OME. In this review we present cytokines identified in otitis media, immunoregulatory [interleukin (IL)-2, IL-10, transforming growth factor-beta]) and allergy associated (IL-4, IL-5, granulocyte-macrophage colony-stimulating factor), as crucial molecular regulators, responsible for chronic inflammation in the middle ear and the chronic condition of OME.

Granulocyte-macrophage colony-stimulating factor and interleukin-2 fusion cDNA for cancer gene immunotherapy

Genetic engineering of tumor cells to express both granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-2 can induce synergistic immune antitumor effects. Paradoxically, the combination has also been reported to down-regulate certain immune functions, highlighting the unpredictability of dual cytokine use. We hypothesized that a GM-CSF and IL-2 fusion transgene (GIFT) could circumvent such limitations yet preserve synergistic features. We designed a fusion cDNA of murine GM-CSF and IL-2. Protein structure computer modeling of GIFT protein predicted for intact ligand binding domains for both cytokines. B16 mouse melanoma cells were gene modified to express GIFT (B16GIFT), and these cells were unable to form tumors in C57bl/6 mice. Irradiated B16GIFT whole-cell tumor vaccine could also induce absolute protective immunity against challenge by live B16 cells. In mice with established melanoma, B16GIFT therapeutic cellular vaccine significantly improved tumor-free survival when compared with B16 expressing both IL-2 and GM-CSF. We show that GIFT induced a significantly greater tumor site recruitment of macrophages than combined GM-CSF and IL-2 and that macrophage recruitment arises from novel chemotactic feature of GIFT. In contrast to suppression by GM-CSF of natural killer (NK) cell recruitment despite coexpression of IL-2, GIFT leads to significant functional NK cell infiltration as confirmed in NK-defective beige mice. In conclusion, we demonstrated that a fusion between GM-CSF and IL-2 can invoke greater antitumor effect than both cytokines in combination, and novel immunobiological properties can arise from such chimeric constructs.

Monocyte surface-bound IL-15 can function as an activating receptor and participate in reverse signaling

IL-15 is a short chain, four-alpha helix cytokine that shares some biological function with IL-2. One striking difference between IL-2 and IL-15 is the ability of monocytes to express IL-15 on their cell surface after activation. In the current study we have investigated the ability of human monocyte cell surface IL-15 to participate in reverse signaling. Cross-linking anti-IL-15 Abs were used as a surrogate ligand for surface IL-15 engagement. Ligation of cell surface-expressed IL-15 induced monocyte adhesion that required the activity of small m.w. GTPases. Reverse signals through surface IL-15 activated the Rho-GTPase Rac3. In addition, engagement of cell surface IL-15 was found to activate a number of signaling pathways, including both extracellular signal-regulated kinase 1/2 and p38, and resulted in the secretion of IL-8. IL-8 production required mitogen-activated protein kinase activity. Thus, the current study has established that cell surface IL-15 is more than just a ligand; it can function as a receptor and participate in reverse signaling that results in cellular adhesion and production of inflammatory cytokines.

Cytokine-based therapy for metastatic renal cell cancer

The use of recombinant gene technology to produce commercially available amounts of cytokines heralded an era of clinical applications of immunotherapy. Although the response rates to cytokine therapies are modest and sometimes occur at the expense of great cost and toxicity, they are proof of the principal that even large tumor burdens can be overcome by purely immune modulation. The interleukins and the interferons have been used in various phases of clinical trials in RCC. The maturation and final results of phase III trials are needed to guide clinical practice. In the meantime, the knowledge gained clinically and in the laboratory should lead to continued improvements and outcomes in immunotherapy for RCC.

Phenotype and antitumor activity of ascitic fluid monocytes in patients with ovarian carcinoma

Monocytes/macrophages (MO/MA) represent a major leukocyte population in the peritoneal cavity of patients with epithelial ovarian cancer (EOC). We examined the phenotypic characteristics and antitumor cell activity of ascitic MO in patients with EOC. MO/MA phenotype was compared with MO in peripheral blood by two- and three-color flow cytometry. Cytotoxic/cytostatic effects of different cytokines on cultured EOC cells were measured by initial labeling or uptake inhibition of [methyl-3H] thymidine. Malignant ascites had higher proportion of MO/MA with the CD14brightCD16+ phenotype than peripheral blood. Cell surface antigen expression of activation and differentiation in peripheral blood and ascites, including CD38, CD40, CD64, and CD86, was higher on CD14brightCD16- and CD14brightCD16+ than on CD14dimCD16- cells. HLA-DR expression was higher on ascitic MO/MA than peripheral blood MO. Significant cytotoxic/cytostatic activity was elicited by treating ascitic MO/MA with interferon-gamma (IFN-gamma) and interleukin-2 (IL-2), but not with interleukin-12, paclitaxel, granulocyte-monocyte colony-stimulating factor (GM-CSF), or tumor necrosis factor-alpha (TNF-alpha). Soluble CD40Lt did not enhance MO/MA cytotoxic activity, and inhibited IFN-gamma or IL-2 induced cytoxicity. We conclude that MO/MA from ascites have elevated proportions of CD14brightCD16+ cells, showing phenotypic features of activation. IFN-gamma induces the cytotoxic and cytostatic activity of MO/MA that is inhibited by CD40Lt.

A phase I trial of immunotherapy with intratumoral adenovirus-interferon-gamma (TG1041) in patients with malignant melanoma

AIMS

Interferon-gamma (IFN-gamma) has been shown to upregulate MHC class I and II expression, and to promote generation of specific antitumor immune responses. We hypothesized that intratumoral administration of an IFN-gamma gene transfer vector facilitates its enhanced local production and may activate effector cells locally. We conducted a phase I dose-escalation study of a replication-deficient adenovirus-interferon-gamma construct (TG1041) to determine safety and tolerability of intratumoral administration, in advanced or locally recurrent melanoma.

METHODS

Patients were enrolled at four successive dose levels: 10(7) infectious units (iu) (n=3), 10(8) iu (n=3), 10(9) iu (n=3), and 10(10) iu (n=2) per injection per week for 3 weeks. TG1041 was injected in the same tumor nodule weekly in each patient. Safety, toxicity, local and distant tumor responses and biologic correlates were evaluated.

RESULTS

A total of 11 patients were enrolled and received the planned three injections per cycle. One patient with stable disease received a second cycle of treatment. A maximum tolerated dose was not reached in this study. No grade 4 toxicities were observed. Two grade 3 toxicities, fever and deep venous thrombosis were observed in one patient. The most frequently reported toxicities were grade 1 pain and redness at the injected site (n=8), and grade 1 fatigue (n=5) patients. Clinical changes observed at the local injected tumor site included erythema (n=5), a minor decrease in size of the injected lesion (n=5) and significant central necrosis by histopathology (n=1). Systemic effects included stable disease in one patient. Correlative studies did not reveal evidence of immunologic activity.

CONCLUSION

Weekly intratumoral administration of TG1041 appears to be safe and well tolerated in patients with advanced melanoma.

Immune effects of escalating doses of granulocyte-macrophage colony-stimulating factor added to a fixed, low-dose, inpatient interleukin-2 regimen: a randomized phase I trial in patients with metastatic melanoma and renal cell carcinoma

Previous studies in cancer patients demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) upregulated the interleukin (IL)-2 receptor on T lymphocytes and monocytes suggesting that subsequently administered IL-2 would produce greater immune effects. The authors treated 21 patients with metastatic renal cell carcinoma and melanoma on a randomized phase I study to test this hypothesis. All 21 patients received a fixed dose of IL-2 (72,000 IU/kg every 8 hours for 5 days) administered intravenously as an inpatient. Patients were randomized to receive IL-2 alone or in combination with GM-CSF at a dose of 125 or 250 mcg/m /d (Sargramostim; Immunex Corporation, WA, U.S.A.) daily for 7 days by subcutaneous injection starting on day 1, the day before IL-2 treatment. The results from this study demonstrated that GM-CSF did not worsen the toxicities produced by IL-2 alone. Grade 3 confusion occurred in four patients, three who received IL-2 alone. No partial or complete tumor responses were seen. Assays of serum soluble IL-2 receptor (sIL2R) and neopterin, measures of T cell and monocyte activation, respectively, demonstrated a significant increase in sIL2R but not neopterin, 24 hours after the first dose of GM-CSF. In combination with IL-2, the higher dose of GM-CSF (250 mcg/m ) produced higher sIL2R levels on days 3 and 7 than the 125-mcg/m dose of GM-CSF or IL-2 alone. Although neopterin levels did not increase after 1 day of GM-CSF, the addition of IL-2 resulted in a significantly increased neopterin level on day 3 at the higher dose of GM-CSF. On day 7, neopterin levels in all three groups were similarly increased over baseline. Ten days after treatment, neopterin levels had returned to normal, but sIL2R levels remained markedly increased (12 fold) over baseline in the higher GM-CSF dose group. The authors conclude that 1) monocyte activation was not significantly enhanced by 1 day of GM-CSF treatment; 2) the 250-mcg/m GM-CSF dose plus IL-2 produced superior T cell activation compared with a lower dose of GM-CSF plus IL-2 or to IL-2 alone; and 3) the combination of GM-CSF and IL-2 was safe and tolerable but was not associated with any clinical responses.

Immunology of the peritoneal cavity: relevance for host-tumor relation

The peritoneal membrane, formed by a single layer of mesothelial cells, lines the largest cavity of the human body. Anatomic structures of the peritoneal cavity, along with resident leukocyte populations, play an important role in the defense against microorganisms invading by breaching the gut integrity or ascending through the female genital tract. Local immune mechanisms in the peritoneal cavity are also important in patients undergoing peritoneal dialysis and in women with endometriosis. There is now extensive evidence demonstrating the significance of peritoneal immune mechanisms in the control of metastatic spread. Leukocytes belonging to both the innate and adaptive immune systems are present in the peritoneal cavity of normal subjects as well as in patients with intra-abdominal cancer. There is now increased understanding of the mechanisms that not only allow the tumor cells to escape the detection and destruction by the host immune system, but also to use the inflammatory mechanisms to promote tumor growth and spread inside the peritoneal cavity. Malignant ascites represents a model for the study of the interaction between tumor cells and the host immune system as well for the analysis of the tumor microenviroment. The peritoneal immune system may be stimulated by intraperitoneal administration of biologic agents. This peritoneal immunotherapy may be used for palliation of malignant ascites, or as a consolidation strategy in patients with minimal residual disease.

Interleukin-2-induced small unilamellar vesicle coalescence

Recombinant human interleukin-2 (rhIL-2) was incorporated in liposomes for potential therapeutic applications using a novel process. In this process, rhIL-2 caused the formation of large, unique multilamellar vesicles (MLVs) from small unilamellar vesicles (SUVs) of dimyristoylphosphatidylcholine (DMPC). Vesicle coalescence occurred most rapidly at 19 degrees C, between the pre- and main phase transition temperatures of DMPC, and showed a dependence upon pH (pH <5.5), ionic strength (>50 mM) and the initial size of the unilamellar vesicles (<or=25 nm). Intermediates (partially coalesced vesicles) within the forming multilamellar structures were identified by freeze-fracture electron microscopy and their presence was corroborated by differential scanning calorimetry. Several distinct steps were identified in the coalescence process. In the initial step, rhIL-2 rapidly bound to the DMPC SUVs. This was followed by a pH-dependent conformational change in the protein, as evidenced by an increase in tryptophan fluorescence intensity. The SUVs then aggregated in large clusters that eventually annealed to form closed MLVs. In this process over 90% of the rhIL-2 was bound to and incorporated within the multilamellar structures.

Comparative assessment of virulence of recombinant vaccinia viruses expressing IL-2 and IL-15 in immunodeficient mice

IL-2 and -15 belong to the four alpha-helix bundle family of cytokines and display a spectrum of overlapping immune functions because of shared signal transducing receptor components of the IL-2 receptor complex. However, recent evidence suggests a nonredundant unique role for IL-15 in the establishment and perhaps maintenance of peripheral natural killer (NK) cell populations in vivo. To explore the contribution of locally released IL-15 on peripheral NK-cell-mediated innate immune responses, we generated a recombinant vaccinia virus that expresses IL-15 and evaluated the course of vaccinial disease in athymic nude mice. Coexpression of IL-15 resulted in the attenuation of virulence of vaccinia virus, and mice inoculated with 10(5) plaque-forming units or less resolved the infection successfully. In contrast, mice inoculated with a similar dose of the control vaccinia virus failed to eliminate the virus and died of generalized vaccinial disease. Enhanced expression of IL-12 and IFN-gamma as well as induction of chemokines were evident in the mice inoculated with IL-15-expressing vaccinia virus in addition to an increase in NK cells in the spleen. However, in this model system, the degree of attenuation in viral virulence attained with coexpression of IL-15 was much less than that achieved with coexpression of IL-2, suggesting that the peripheral NK-cell-mediated events are more responsive to IL-2 than to IL-15.

Cytokines and chronic fatigue syndrome

Chronic fatigue syndrome (CFS) patients show evidence of immune activation, as demonstrated by increased numbers of activated T lymphocytes, including cytotoxic T cells, as well as elevated levels of circulating cytokines. Nevertheless, immune cell function of CFS patients is poor, with low natural killer cell cytotoxicity (NKCC), poor lymphocyte response to mitogens in culture, and frequent immunoglobulin deficiencies, most often IgG1 and IgG3. Immune dysfunction in CFS, with predominance of so-called T-helper type 2 and proinflammatory cytokines, can be episodic and associated with either cause or effect of the physiological and psychological function derangement and/or activation of latent viruses or other pathogens. The interplay of these factors can account for the perpetuation of disease with remission/exacerbation cycles. A T-helper type 2 predominance has been seen among Gulf War syndrome patients and this feature may also be present in other related disorders, such as multiple chemical sensitivity. Therapeutic intervention aimed at induction of a more favorable cytokine expression pattern and immune status appears promising.

Effect of perilesional injections of PEG-interleukin-2 on basal cell carcinoma

BACKGROUND

Multiple modalities are available for the treatment of basal cell carcinoma (BCC). The most commonly used modalities include simple excision, Mohs micrographic surgery, curettage and electrodessication, cryosurgery, and irradiation therapy. Interleukin-2 (IL-2) is a cytokine produced chiefly by activated T lymphocytes and has effects on various components of the immune system. Until now the primary clinical use of IL-2 has been in advanced stages of metastatic melanoma and renal cell carcinoma. Systemic administration of IL-2 is known to cause significant toxicity.

OBJECTIVE

The objective of this study was to evaluate the therapeutic efficacy and safety of perilesional PEG-IL-2 injections in patients with BCC in an open label, uncontrolled pilot study.

METHODS

Patients with histologically confirmed primary BCC over 18 years of age were included in the study. Lesions were treated by injecting a total volume of 0.5 cc of IL-2 in a radial fashion in the subcutaneous tissue. Injection dosages ranged from 3000 to 1,200, 000 IU in one to four weekly dosages. A total of 12 tumors were treated in eight patients.

RESULTS

Overall response rates were as follows: complete response in 8 of 12 treated tumors (66.6% cure rate), partial response in 3 of 12 injected tumors (25% partial response rate), stable disease with no improvement in 1 treatment site (8.4%). Side effects included local pain, swelling, and erythema, and in one patient flulike symptoms. There were no significant changes of blood tests as compared to baseline levels.

CONCLUSIONS

The therapeutic response induced by perilesional PEG-IL-2 injections was found to be an encouraging, safe, and well-tolerated treatment of BCC. Further studies including a larger patient population and long-term follow-up are necessary in order to substantiate these findings.

IL-2 induces the association of IL-2Rbeta, lyn, and MAP kinase ERK-1 in human neutrophils

IL-2, first identified as a T cell growth factor, has been proven to activate many cell types including polymorphonuclear neutrophils (PMN3). However, the mechanisms involved in PMN activation, especially the signaling pathways used by the IL-2R, are currently unknown. Here we demonstrate that IL-2 has the ability to induce protein tyrosine kinases in human PMN, and we provide the first evidence that lyn kinase is activated and physically associated with MAP kinase/ERK1. Co-immunoprecipitation experiments with anti-IL-2Rbeta and Western blotting with anti-p53/56lym revealed that lyn protein was present in IL-2R precipitates and that the association of lyn with IL-2Rbeta was markedly elevated by IL-2 stimulation. Furthermore the activity of lyn kinase, evaluated by an in vitro kinase assay with enolase as a substrate, increased following IL-2 stimulation. Another important finding was that, upon IL-2 activation, MAPK/ERK1 was also phosphorylated in PMN. A direct association between lyn and ERK1 was initially demonstrated by co-immunoprecipitation/Western blotting and then definitively proven by the use of a GST-ERK1 fusion protein. We showed that ERK1 binds lyn only in IL-2 stimulated PMN, but not in unstimulated PMN. These results suggest that IL-2 can promote the association of lyn protein tyrosine kinase with IL-2Rbeta as well as the direct binding of MAPK/ERK1 to lyn. The signaling pathway utilized by human PMN in response to IL-2 may thus involve the association of lyn with IL-2Rbeta and the activation process also triggers the recruitment and activation of a specific ERK.

Augmentation of 17-1A-induced antibody-dependent cellular cytotoxicity by the triple cytokine combination of interferon-alpha, interleukin-2, and interleukin-12

Previously, interferon-alpha (IFN-alpha), interleukin-2 (IL-2), and interleukin-12 (IL-12) were shown to increase the antibody-dependent cellular cytotoxicity (ADCC) induced by the murine monoclonal antibody 17-1A, which recognizes the tumor-associated antigen EpCAM. In this study, the authors wanted to determine whether the combination of these three cytokines would yield greater cytotoxicity than the single cytokines. For cytotoxicity assessment, a new flow cytometric assay was used that allows the analysis of long-term ADCC exerted by macrophages. Peripheral blood mononuclear cells from healthy donors were used as effector cells against the colorectal carcinoma cell line HT29 at a low effector-to-target ratio of 4.5:1. With this test, the effectiveness of the combinations IL-2 and IFN-alpha, IL-2 and IL-12, and IL-12 and IFN-alpha were compared with each other. The combinations IL-2 plus IL-12 and IFN-alpha plus IL-12 were more potent at the concentrations tested. Furthermore, the triple cytokine combination of IFN-alpha, IL-2, and IL-12 revealed significantly greater ADCC than dual cytokine combinations. Next, CD14+, CD4+, and CD4- cells were isolated by paramagnetic beads and magnetic activated cell sorter (MACS) columns. The CD14+ and CD4- cell populations contained the ADCC effectors. The addition of CD4+ cells to CD14+ or CD4- cells resulted in augmented ADCC, indicating that cooperation between immune cells occurs. These results suggest that multiple cytokine combinations with monoclonal antibodies may be more effective for cancer immunotherapy.

IL-2 enhances standard IFNgamma/LPS activation of macrophage cytotoxicity to human ovarian carcinoma in vitro: a potential for adoptive cellular immunotherapy

OBJECTIVE

The objective was to evaluate the enhancement of human peritoneal macrophage cytotoxic in vitro activity by the addition of interleukin-2 (IL-2) to the standard interferon gama (IFNgamma) and lipopolysaccharide (LPS) activation procedure used for cellular adoptive immunotherapy in a human ovarian cancer system. This cytotoxic effect of these activated macrophages was tested on cells from ovarian cancers of various stages, histology type, and grade, both prior to chemotherapy and at recurrence, in ovarian carcinoma cells lines and normal cells. Increased activation of the macrophage may make it a better candidate for intraperitoneal cellular adoptive immunotherapy as a component of ovarian cancer therapy. This was not a study of the mechanism of macrophage killing.

METHODS

Ascites specimens were collected from 24 ovarian cancer patients at the time of surgery or by paracentesis. The mononuclear cell fraction was isolated by discontinuous density gradient centrifugation and used as a cellular source of peritoneal macrophages (PMs) and primary cultured ovarian cancer cells. PMs were separated by 1-h adhesion followed by intensive washing to remove floating cells. The floating cells were cultured for 24 h which left the cancer cells attached after unattached cells were removed by washing. These cells formed a monolayer of cancer cells, which could be subcultured in 22 patients. The cells from the third to fifth passages were used as target cells without coculture with other cells. PMs were identified by latex ingestion, and their purity after isolation by adhesion culture was tested by flow cytometry and immunofluorescence. PMs were activated by culturing in the presence of IFNgamma, with or without IL-2, for 18 h followed by the addition of LPS 6 h prior to use as effector cells in cytotoxicity assays. Ovarian cancer cells of both established cell lines and primary cultures were labeled with (51)Cr and utilized as target cells to quantitatively measure PM-mediated cytotoxicity. Ovarian cancer cells were also cocultured with PMs for morphologic observations to provide supporting evidence to the cytotoxicity assays.

RESULTS

IL-2 enhances the cytotoxicity of the standard IFNgamma/LPS macrophage activation in this system. Peritoneal macrophages so activated are cytotoxic to autologous and allogenic primary cultured ovarian tumors and to ovarian carcinoma cell lines. The macrophages are cytotoxic to cells both prior to treatment and at recurrence, but the data from the few recurrent patients did reach statistical significance. This cytotoxicity is not MHC associated. Normal cells are minimally affected.

CONCLUSIONS

IL-2 augmented the standard IFNgamma/LPS method of activating peritoneal macrophage cell killing of human ovarian cancer cells in this in vitro system. The cell killing occurred with autologous and allogenic tumor cells from patients with primary and possibly recurrent tumors. Activated PMs minimally affected the normal cells tested. This enhanced activation may improve the disappointing results of previous adoptive cellular immunotherapy human trials and should be considered for ovarian cancer clinical trials.

Influence of peri-operative immunotherapy on serum cytokines and soluble cytokine receptors in patients undergoing surgery for colorectal cancer

OBJECTIVE

The cellular immune response is suppressed following surgery for colorectal cancer. As cytokines influence the patient's immunological responsiveness, we have measured serum cytokines and their soluble receptors in patients receiving peri-operative immunotherapy for colorectal cancer.

PATIENTS AND METHODS

Fifty-two patients were randomized to receive low dose recombinant IL-2 (rIL-2) alone; rIL-2 with interferon-alpha (IFN-α) or no immunotherapy. Serum cytokines and cytokine receptor levels were measured preoperatively and on post-operative days 1, 4, 7 and 10 using ELISA kits.

RESULTS

Circulating levels of IFN-γ were undetectable in the majority of patients, although IFN-γR levels were increased in all three groups on the first post-operative day (P < 0.05). Similarly, IL-2 was undetectable in most subjects and not enhanced by treatment. However, IL-2R was significantly induced in all patients (P < 0.001), and these levels were higher in both treatment groups when compared with control (P < 0.005). Tumour necrosis factor-alpha (TNF-α) was universally undetectable, but the TNF-R p55 and p75 subunits were induced in all patients (P < 0.005); and as with IL-2R, this was greater in the treatment groups (P < 0.01). Finally, IL-6 production was induced in all groups (P < 0.005), but this was only noted on day 1.

CONCLUSION

Soluble cytokine receptors are induced by surgery, and levels of IL-2R and TNF-R are enhanced by exogenous rIL-2 and rIL-2 with IFN-α. This augmentation suggests increased immunocompetence associated with low dose peri-operative immunotherapy.

Activation of NF-kappaB in Mycobacterium tuberculosis- induced interleukin-2 receptor expression in mononuclear phagocytes

Soluble interleukin-2 receptor-alpha (IL-2Ralpha) has been reported to be increased in the sera of patients with advanced tuberculosis, and levels decline after therapy in accordance with improvement of radiologic findings. We investigated expression of the IL-2Ralpha in bronchoalveolar lavage (BAL) cells in active pulmonary tuberculosis, and evaluated the mechanism Mycobacterium tuberculosis induces in the IL-2Ralpha using the THP-1 mononuclear phagocyte cell line. We found IL-2Ralpha expression to be increased in BAL cells from involved sites of active pulmonary tuberculosis. Expression of the alpha-chain of IL-2Ralpha on peripheral blood monocytes (PBM) was induced by M. tuberculosis by flow cytometry evaluation. Northern analysis demonstrated increased IL-2Ralpha gene expression after stimulation with M. tuberculosis which was further induced by interferon-gamma (IFN-gamma). The IL-2Ralpha promoter containing the nuclear factor kappa B (NF-kappaB) site was transcriptionally induced by M. tuberculosis and this NF-kappaB site could confer inducibility to a heterologous herpes thymidine kinase (TK) promoter by M. tuberculosis. Electrophoretic mobility shift assays (EMSAs) revealed specific binding of nuclear protein to the NF-kappaB site upon induction with M. tuberculosis. Using antibodies against the p50 and p65 subunits of NF-kappaB in EMSAs, the involvement of both p50 and p65 proteins was further demonstrated. Functional expression of the IL-2Ralpha on mononuclear phagocytes in M. tuberculosis infection may play an important immunomodulatory role in the host response.

Interleukin-2 affects cochlear function gradually but reversibly

Interleukin-2 (IL-2), one of the chemical mediators produced by helper T cells, activates its target cells via its receptor and induces inflammatory reactions indirectly. In this study, IL-2 was instilled into the round window niche of rats and the electrophysiological effects of inflammation on the inner ear were evaluated by a frequency-specific auditory brainstem response (ABR) technique. ABR threshold curves and intensity-latency (I-L) curves were investigated. In most cases, moderate sensorineural hearing loss (SNHL) was observed in the high-frequency areas (16-31.5 kHz). In the time course investigation of I-L curves, the responses of SNHL type appeared only 1 day after instillation (day 1) gradually becoming more prominent, to become most pronounced on days 5-7. The electrophysiological impairment was reversible within 2 weeks. Differing degrees of responsiveness of effusion production were observed following the instillation of IL-2, varying from pronounced middle ear effusion causing rather severe mixed hearing loss, to complete lack of effusion. Inflammation induced by IL-2 affects cochlear function gradually but reversibly.

Cytokine and hepatitis B virus DNA co-immunizations enhance cellular and humoral immune responses to the middle but not to the large hepatitis B virus surface antigen in mice

Genetic immunization is a potentially useful strategy to prevent or treat hepatitis B virus (HBV) infection. We have previously shown that HBV envelope proteins are highly immunogenic using this technique. The large envelope protein (LHBs), however, induced significantly weaker humoral and cellular immune responses when compared with the middle envelope protein (MHBs). We studied the effect of co-immunizations with cytokine DNA expression constructs encoding for interleukin (IL)-2 and (GM-CSF) on the immunogenicity of LHBs at the B-and T-cell level. Co-immunizations of mice with plasmids encoding for MHBs and IL-2 or GM-CSF increased anti-HBs responses, helper T-cell proliferative activity, and cytotoxic T lymphocyte (CTL) killing. In contrast, co-immunizations of plasmids encoding for LHBs and IL-2 or GM-CSF had no effect on humoral and cellular immune responses. LHBs did not inhibit the production or secretion of IL-2 and GM-CSF. In addition, IL-2, tumor necrosis factor alfa (TNF-alpha), and interferon gamma (IFN-gamma) had no suppressive effect on HBV envelope protein expression in vitro. Based on these data, MHBs, but not LHBs, genetic immunization can be augmented by IL-2 or GM-CSF cytokines.

Interleukin-2 inhibits HIV-1 replication in human macrophages by modulating expression of CD4 and CC-chemokine receptor-5

OBJECTIVE

To determine the effect of recombinant human interleukin (IL)-2 on HIV-1 replication and macrophage colony stimulating factor (M-CSF) production by HIV-1-infected monocyte-derived macrophages (MDM).

DESIGN

Therapeutic use of IL-2 increases the number and function of CD4+ T cells. IL-2 also increases M-CSF production and M-CSF receptor expression by human monocytes, but the subsequent effects on HIV-1 replication in MDM have yet to be determined. MDM from HIV-1-seronegative donors were cultured in the presence and absence of IL-2 and infected with HIV-1. Harvested supernatants were monitored for reverse transcriptase activity and M-CSF production.

RESULTS

Reverse transcriptase activity was significantly lower when MDM cultures were treated with IL-2 for 10 days prior to infection with HIV-1. IL-2 did not stimulate production of inhibitory chemokines or cytokines, but FACS analysis revealed that expression of CD4, the primary HIV-1 receptor, and CC-chemokine receptor-5, a coreceptor used by macrophage-tropic viruses, are down modulated after treatment with IL-2.

CONCLUSION

IL-2 may not only be of benefit in restoring immune function in AIDS patients, but may also help to prevent the infection of healthy macrophages by decreasing their expression of HIV-1 receptors.

The immunological co-adjuvant action of liposomal interleukin-2: the role of mode of localisation of the cytokine and antigen in the vesicles

In experiments designed to study the co-adjuvant action of interleukin-2, a model antigen (tetanus toxoid) was passively entrapped in, or covalently coupled to multilamellar liposomes in the presence or absence of interleukin-2 (IL-2). When present, IL-2 was either co-entrapped with the toxoid, entrapped alone in liposomes with toxoid coupled to their surface, or coupled to the surface of liposomes with entrapped toxoid. The role of spatial localization of IL-2 within the liposomal structure (vis a vis that of the toxoid) was studied in terms of its immunoadjuvant action in vivo. Male CD-1 mice were injected intramuscularly twice with a variety of toxoid-containing liposomal preparations in the absence or presence of IL-2 incorporated in the same liposomes as above. In some experiments mice were immunized with liposomal toxoid mixed with separately entrapped IL-2. Results show that IL-2 augments significantly secondary immune responses (IgG1, IgGa, IgG2b subclasses) against the liposomal toxoid (up to 15-fold compared with the liposomal toxoid alone), regardless of cytokine and antigen mode of accommodation in the liposomal structure but only when both are present in the same vesicles. It is suggested that liposomal IL-2 may prove useful as a co-adjuvant for vaccines which are weak or ineffective.

Inhibition by sphingosine of leukemic cell killing by human monocytes activated with interleukin-2: a possible role of protein kinase C

Sphingosine and its analogs, which inhibit protein kinase C (PKC), are known to be potent inducers of apoptosis in tumor cells. However, we were concerned that sphingosine might also interfere with anti-tumor cells of the immune system. Therefore, we evaluated the effect of sphingosine on activation of human monocytes by interleukin-2 (IL-2) for killing of leukemic cells. Monocytes, purified by elutriation and adherence, were activated with IL-2 or interferon-gamma (IFN-gamma) in the presence or absence of sphingosine or another inhibitor for 18 h. Then the monocytes were washed and the culture medium was replaced with fresh medium to remove the sphingosine. HL- 60 and K562 leukemic cells were added to the monocyte cultures. Over the next 48 h, the cytotoxic activity of the monocytes towards the leukemic cells was assessed by means of an 111-indium-releasing assay. IL-2-activated monocytes lysed 48 +/- 3% of HL-60 cells and 44 +/- 3% of K562 cells. Sphingosine, dihydrosphingosine, N,N-dimethylsphingosine, and the PKC inhibitor H7 inhibited the activation of monocytes by IL-2, blocking cytotoxic activity against the leukemic cells by approximately 75%. These inhibitors were not toxic to monocytes at the concentrations used. In a PKC assay, sphingosine and H7 inhibited PKC activity in IL-2-treated monocytes. Thus, sphingosines, by inhibiting PKC activity, inhibited activation of monocytes by IL-2, which inhibited the killing of leukemic cells.

Abnormal Myelocytic Cell Development in Interleukin-2 (IL-2)–Deficient Mice: Evidence for the Involvement of IL-2 in Myelopoiesis

Mice lacking interleukin-2 (IL-2) developed a severe hematopoietic disorder characterized by the abnormal development of myeloid cells and neutropenia. Analysis of the bone marrow of IL-2–deficient (IL-2−/−) mice showed that the number of mature polymorphonuclear cells was decreased by 65% to 75%, and granulocyte/macrophage precursor cells were reduced by 50%. Bone marrow cells from IL-2−/− mice were unable to sustain myelopoiesis in lethally irradiated mice and in long-term bone marrow cultures (LTBMC). The addition of exogenous IL-2 to LTBMC of IL-2−/− cells partially restored hematopoietic progenitor activity. In the bone marrow of wild-type mice, immature (Mac-1lo) myeloid cells, including myeloblasts and promyelocytes, constitutively expressed the β-chain of the IL-2R, and the number of Mac-1loIL-2Rβ+ cells was increased by twofold to threefold in IL-2−/− mice. During culture in the presence of IL-2 and the absence of stromal cells, Mac-1loIL-2Rβ+ immature myeloid cells proliferated and gave rise to mature granulocytes and macrophages. Collectively, these observations indicate that defective myelopoiesis in IL-2−/− mice is at least in part a consequence of their direct dependency on IL-2, and by regulating the growth of immature myeloid cells, IL-2 plays an important role in the homeostatic regulation of myelocytic cell generation.

Hematopoietic progenitor cell transplantation in breast cancer: current status and future directions

Breast cancer remains the second leading cause of cancer death despite numerous advances in medical science. In vitro, preclinical, and clinical trials have shown that chemotherapy dose intensity is an important component of therapy. Many clinical trials addressing the use of high-dose chemotherapy and hematopoietic cellular rescue have been conducted over the past decade. Early trials undertaken in heavily pretreated patients who had metastatic disease were associated with high treatment-related mortality rates; good response rates were noted but overall survivals were short. Subsequent technological advances, including the use of recombinant hematopoietic growth factors and peripheral blood progenitor cells as the source of cellular rescue, have dramatically lowered the morbidity and mortality of the procedure, as well as shortened hospital stay and markedly reduced cost. As a result, the high-dose chemotherapy approach has been used earlier in the disease course, both in patients with metastatic disease who were responding and in the adjuvant setting in patients at high risk for relapse. Results of many of these phase II trials are extremely encouraging, and phase III prospective, randomized trials comparing autotransplant to conventional approaches are currently under way. This review discusses past, current, and future initiatives of this modality. Included is a discussion of new preparative regimens, the addition of agents such as biochemical modifiers to enhance antitumor activity, and issues regarding timing of autotransplant, stem cell technology, use of allogeneic stem cells, and posttransplantation therapies.

Interleukin-15 augments superoxide production and microbicidal activity of human monocytes against Candida albicans

Interleukin-15 (IL-15) is a newly described cytokine that shares biological activities with IL-2. We report here results demonstrating the ability of IL-15 to enhance superoxide production and antifungal activity of human monocytes. After 18 and 48 h of treatment with IL-15, human elutriated monocytes manifested enhanced superoxide production in response to either phorbol myristate acetate or opsonized Candida albicans blastoconidia. Similar results were obtained when monocytes were treated with IL-2, but to a lesser extent. Combination studies with IL-15 and IL-2 showed no additive or synergistic effects. Following incubation of monocytes with IL-15 for 18 h, there was no significant increase in mRNA transcripts for components of the NADPH oxidase complex, p40-phox, p47-phox, and gp91-phox, suggesting a posttranscriptional modulation of enhanced superoxide production. Antibodies against the gamma chain of the IL-2 receptor and, to a lesser extent, against the beta chain partially abrogated the IL-15-mediated enhanced superoxide production. Additionally, human monocytes showed enhanced killing activity against C. albicans after 18 h of incubation with IL-15 or IL-2, but this treatment did not enhance the ability of these cells to phagocytose the organism. In addition, the enhanced fungicidal activity seen after 18 h of treatment was no longer detectable after 48 h of cytokine treatment. Culture supernatants from the IL-15-treated monocytes were assayed for the presence of other proinflammatory cytokines. IL-15 treatment did not induce the release of detectable levels of tumor necrosis factor alpha, IL-1beta, or IL-12. Our results indicate that IL-15 upregulates the microbicidal activity of human monocytes against C. albicans.

Signaling from the IL-2 receptor to the nucleus

Interleukin-2 has pleiotropic actions on the immune system and plays a vital role in the modulation of immune responses. Our current understanding of IL-2 signaling has resulted from in vitro studies that have identified the signaling pathways activated by IL-2, including the Jak-STAT pathways, and from in vivo studies that have analyzed mice in which IL-2, each chain of the receptor, as well a number of signaling molecules have been individually targeted by homologous recombination. Moreover, mutations in IL-2Ralpha, gamma(c) and Jak3 have been found in patients with severe combined immunodeficiency. In addition, with the discovery that two components of the receptor, IL-2Rbeta and gamma(c), are shared by other cytokine receptors, we have an enhanced appreciation of the contributions of these molecules towards cytokine specificity, pleiotropy and redundancy.

The Antineoplastic Agent Bryostatin-1 Induces Proinflammatory Cytokine Production in Human Monocytes: Synergy With Interleukin-2 and Modulation of Interleukin-2Rγ Chain Expression

The antineoplastic agent bryostatin-1 (bryo-1) possesses powerful immunomodulatory properties and can function as a biological response modifier in vivo. However, there is currently little information regarding the effects of bryo-1 on cells of the monocytic lineage. In this study, we demonstrate that bryo-1 can potently induce the production of proinflammatory cytokines from human peripheral blood monocytes. Stimulation of monocytes with subnanomolar concentrations of bryo-1 significantly upregulated the constitutive levels of interleukin-8 (IL-8) mRNA and induced the expression of IL-1β, tumor necrosis factor-α (TNF-α), and IL-6 mRNA in a time and dose-dependent manner. Accordingly, secretion of all four proinflammatory cytokines was induced after monocyte exposure to bryo-1. Furthermore, we showed that bryo-1 selectively synergized with IL-2 in triggering monocyte activation, and this effect seemed to be dependent, at least in part, on the ability of bryo-1 to upregulate IL-2Rγ chain expression. Finally, we demonstrated that the responses of monocytes to bryo-1 could be blocked by the protein kinase C (PKC) inhibitors staurosporine and UCN-01, indicating a role for PKC in monocyte activation by bryo-1. These results show for the first time that bryo-1 is a powerful activator of human monocytes and suggest that stimulation of monokine secretion by bryo-1 may represent at least one of the mechanisms responsible for the in vivo antitumor activity of this drug.

Activated long-term peripheral blood cultures as preparation for adoptive alloreactive cell therapy in cancer patients

Different modes of in vitro activation of peripheral blood mononuclear cells (PBMC) were compared for their effect on long-term propagation. PBMC cultures were activated by short exposures to the mitogen phytohemagglutinin (PHA) and the CD3 complex, with or without secondary signals provided by ligands of CD28 costimulatory molecules. Activation and long-term cultures were carried out in the presence of recombinant interleukin-2 (rIL-2). Addition of supernatant derived from IL-2-activated PBMC improved culture cell yield. Cumulative fold expansions ranged between 10(3) and 10(5) within 21 days. The highest cell yield was found after PHA activation. Fewer cells were obtained after activation with a combination of CD3 and CD28, and even fewer were obtained after CD3 activation alone. An increase in CD8+ and CD56+ cells, without change in CD4+ cells, was found in activated cultures when compared with fresh PBMC. Non-MHC-restricted cytotoxic activity was documented in all activated cultures. Cytotoxic activity per culture was highest in PHA-activated PBMC because of the high cell yield on the day of harvest. Successful in vitro expansion of PBMC might be helpful for gene transfer into T lymphocytes, as well as for the induction of an antitumor response, particularly for prevention and treatment of relapse of hematologic malignancies following allogeneic or autologous bone marrow transplantation.