Purification and chemical characterization of the receptor for interleukin 2 from activated human T lymphocytes and from a human T-cell lymphoma cell line

Chemokine receptor 7 (CCR7)-expression and IFNγ production define vaccine-specific canine T-cell subsets

Canines suffer from and serve as strong translational animals models for many immunological disorders and infectious diseases. Routine vaccination has been a mainstay of protecting dogs through the stimulation of robust antibody responses and expansion of memory T-cell populations. Commercially available reagents and described techniques are limited for identifying and characterizing canine T-cell subsets and evaluating T-cell-specific effector function. To define reagents for delineating naïve versus activated T-cells and identify antigen-specific T-cells, we tested anti-human and anti-bovine T-cell specific cell surface marker reagents for cross-reactivity with canine peripheral blood mononuclear cells (PBMCs. Both CD4(+) and CD8(+) T-cells from healthy canine donors showed reactivity to CCL19-Ig, a CCR7 ligand, and coexpression with CD62L. An in vitro stimulation with concanavalin A validated downregulation of CCR7 and CD62L expression on stimulated healthy control PBMCs, consistent with an activated T-cell phenotype. Anti-IFNγ antibodies identified antigen-specific IFNγ-producing CD4(+) and CD8(+) T-cells upon in vitro vaccine antigen PBMC stimulation. PBMC isolation within 24h of sample collection allowed for efficienT-cell recovery and accurate T-cell effector function characterization. These data provide a reagent and techniques platform via flow cytometry for identifying canine T-cell subsets and characterizing circulating antigen-specific canine T-cells for potential use in diagnostic and field settings.

Combined dysfunctions of immune cells predict nosocomial infection in critically ill patients

BACKGROUND

Nosocomial infection occurs commonly in intensive care units (ICUs). Although critical illness is associated with immune activation, the prevalence of nosocomial infections suggests concomitant immune suppression. This study examined the temporal occurrence of immune dysfunction across three immune cell types, and their relationship with the development of nosocomial infection.

METHODS

A prospective observational cohort study was undertaken in a teaching hospital general ICU. Critically ill patients were recruited and underwent serial examination of immune status, namely percentage regulatory T-cells (Tregs), monocyte deactivation (by expression) and neutrophil dysfunction (by CD88 expression). The occurrence of nosocomial infection was determined using pre-defined, objective criteria.

RESULTS

Ninety-six patients were recruited, of whom 95 had data available for analysis. Relative to healthy controls, percentage Tregs were elevated 6-10 days after admission, while monocyte HLA-DR and neutrophil CD88 showed broader depression across time points measured. Thirty-three patients (35%) developed nosocomial infection, and patients developing nosocomial infection showed significantly greater immune dysfunction by the measures used. Tregs and neutrophil dysfunction remained significantly predictive of infection in a Cox hazards model correcting for time effects and clinical confounders {hazard ratio (HR) 2.4 [95% confidence interval (CI) 1.1-5.4] and 6.9 (95% CI 1.6-30), respectively, P=0.001}. Cumulative immune dysfunction resulted in a progressive risk of infection, rising from no cases in patients with no dysfunction to 75% of patients with dysfunction of all three cell types (P=0.0004).

CONCLUSIONS

Dysfunctions of T-cells, monocytes, and neutrophils predict acquisition of nosocomial infection, and combine additively to stratify risk of nosocomial infection in the critically ill.

Identification of novel Interleukin-2 inhibitors through computational approaches

Interleukin-2 (IL-2), is a 15.5-kDa cytokine that is now emerging as a target in drug discovery for novel therapeutic approaches in several autoimmune disorders. In an attempt to identify new inhibitors for the IL-2/IL-2R interaction, virtual screening (VS) was performed. Four different docking programs (GOLD, FlexX, Glide, and LigandFit) in combination with several scoring functions were used to identify novel IL-2/IL-2R interaction inhibitors.VSof a database of 6,000compounds resulted in the identification of three novel and moderately active hits with IC50 values ranging from 6.6 to 44.3 μM. Furthermore, the effect of these three compounds on the expression of IL-2Rα was assessed. The three active hits showed dose-dependent inhibitory effects on the expression of IL-2Rα with an IC50 range of 5.8 to 140μM. The cytotoxicity of these active hits was assessed using three normal cell-lines: bovine kidney cell-line (MDBK), mouse fibroblast cell-line (3T3), and rat hepatocytes cell-line (CC-1).Thecompoundswere found to have negligible cytotoxicity compared to their IC50 as IL-2/IL-2R interaction inhibitors. These results demonstrate that our VS protocol can identify novel inhibitors for IL-2/IL-2R interaction that effectively suppress IL-2 production, as well as the expression of IL-2Rα. Optimization of these molecules could lead to improved and effective anti-inflammatory therapeutics.

Cell-specific protein phenotypes for the autoimmune locus IL2RA using a genotype-selectable human bioresource

Genome-wide association studies (GWAS) have identified over 300 regions associated with more than 70 common diseases. However, identifying causal genes within an associated region remains a major challenge. One approach to resolving causal genes is through the dissection of gene-phenotype correlations. Here we use polychromatic flow cytometry to show that differences in surface expression of the human interleukin-2 (IL-2) receptor alpha (IL2RA, or CD25) protein are restricted to particular immune cell types and correlate with several haplotypes in the IL2RA region that have previously been associated with two autoimmune diseases, type 1 diabetes (T1D) and multiple sclerosis. We confirm our strongest gene-phenotype correlation at the RNA level by allele-specific expression (ASE). We also define key parameters for the design and implementation of post-GWAS gene-phenotype investigations and demonstrate the usefulness of a large bioresource of genotype-selectable normal donors from whom fresh, primary cells can be analyzed.

Identification, purification and characterization of a receptor for dengue virus-induced macrophage cytotoxin (CF2) from murine T cells

Dengue type-2 virus infection in mice induces a subpopulation of T lymphocytes to produce a cytokine cytotoxic factor, which induces macrophages (Mphi) to produce a biologically active cytotoxic cytokine, the Mphi cytotoxin (CF2). Previously we have identified the presence of intermediate-affinity receptors for CF2 on mouse peritoneal Mphi. The present study was undertaken to identify the CF2-receptors (CF2-R) on murine T cells followed by their purification and characterization. Receptor binding assay and Scatchard analysis revealed single, high-affinity (1.0309 nM) receptors for CF2 on T cells (22000 receptors per cell). The binding of [125I]CF2 on murine T cells was saturable and specific. Furthermore, CF2-R was purified from normal mouse T cell plasma membrane by affinity chromatography followed by reversed-phase high-pressure liquid chromatography. The presence of CF2-R was confirmed by indirect dot-blot assay and its binding with [125I]CF2. The purified CF2-R is a 90-95-kDa protein as characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis. The chemical crosslinking of [125I]CF2 and its receptor complex showed a product of 100-110 kDa on different subpopulations of murine T cells. The pretreatment of target cells with anti-CF2-R antisera inhibited the cytotoxic activity of CF2 in a dose-dependent manner and thus confirmed the biological significance of CF2-R. Moreover, the presence of CF2-R was also identified on normal human peripheral blood mononuclear cells and T and B cells by crosslinking with [125I]CF2, thus revealing the possible role of CF2 and CF2-R in the immunopathogenesis of dengue virus disease.

Stress regulates the lymphocyte homing receptor CD62L (L-selectin)

Based on a previous study showing that panic disorder patients had increased expression of na ve phenotype lymphocytes (CD45RA+ and CD62L+), increased plasma cortisol, as well as decreased interleukin-2 (IL-2) producion, we hypothesized that changes in the percentage of expression of these lymphocyte surface molecules could be related to the substances released by the hypothalamic-pituitary-adrenal (HPA) axis and possibly associated to panic disorder (cortisol, IL-2, serotonin and epinephrine). In order to study the altered expression, blood mononuclear cells of normal volunteers were stimulated with mitogen, in the presence of dexamethasone, IL-2, serotonin and epinephrin. CD62L is decreased by IL-2 in vitro. Serotonin and epinephrine did not promote changes in the expression of these surface molecules. The results of the ex vivo study are in agreement with a previous clinical study with panic patients. It could be suggested that stress is responsible for certain immunologic dysfunctions and new studies should be conducted.

Daclizumab, a humanized anti-interleukin-2 receptor alpha chain antibody, for treatment of acute graft-versus-host disease

Daclizumab, a humanized monoclonal IgG1 directed against the  chain of the interleukin-2 receptor (IL-2R), is a competitive inhibitor of IL-2 on activated lymphocytes. To test the hypothesis that specific inhibition of activated lymphocytes in patients with ongoing acute graft-versus-host disease (GVHD) might ameliorate the process, we treated 43 patients with advanced or steroid-refractory GVHD with daclizumab. The first cohort of 24 patients was treated with daclizumab 1 mg/kg on days 1, 8, 15, 22, and 29. On day 43, the complete response (CR) rate was 29% (95% confidence interval [CI], 13%-51%). Survival on day 120 was 29% (95% CI, 13%-51%). A second cohort of 19 patients was treated with daclizumab 1 mg/kg on days 1, 4, 8, 15, and 22. For these patients, the CR rate on day 43 was 47% (95% CI, 24%-71%), and survival on day 120 was 53% (95% CI, 29%-76%). There were no infusion-related reactions and no serious side effects related to daclizumab. Following treatment, there was a reduction in serum concentrations of soluble IL-2R and peripheral blood CD3 + 25+ lymphocytes, but these changes were not predictive of response. Daclizumab has substantial activity for the treatment of acute GVHD, and the second regimen evaluated is recommended for a controlled study. (Blood, 2000; 95:83-89)

Daclizumab, a humanized anti-interleukin-2 receptor alpha chain antibody, for treatment of acute graft-versus-host disease

Daclizumab, a humanized monoclonal IgG1 directed against the  chain of the interleukin-2 receptor (IL-2R), is a competitive inhibitor of IL-2 on activated lymphocytes. To test the hypothesis that specific inhibition of activated lymphocytes in patients with ongoing acute graft-versus-host disease (GVHD) might ameliorate the process, we treated 43 patients with advanced or steroid-refractory GVHD with daclizumab. The first cohort of 24 patients was treated with daclizumab 1 mg/kg on days 1, 8, 15, 22, and 29. On day 43, the complete response (CR) rate was 29% (95% confidence interval [CI], 13%-51%). Survival on day 120 was 29% (95% CI, 13%-51%). A second cohort of 19 patients was treated with daclizumab 1 mg/kg on days 1, 4, 8, 15, and 22. For these patients, the CR rate on day 43 was 47% (95% CI, 24%-71%), and survival on day 120 was 53% (95% CI, 29%-76%). There were no infusion-related reactions and no serious side effects related to daclizumab. Following treatment, there was a reduction in serum concentrations of soluble IL-2R and peripheral blood CD3 + 25+ lymphocytes, but these changes were not predictive of response. Daclizumab has substantial activity for the treatment of acute GVHD, and the second regimen evaluated is recommended for a controlled study. (Blood, 2000; 95:83-89)

Interleukin-2 directly increases albumin permeability of bovine and human vascular endothelium in vitro

The direct effects of interleukin-2 (IL-2) on albumin permeability of cultured bovine pulmonary artery endothelial cell (BPAEC) and human arterial endothelial cell (HAEC) monolayers were studied. BPAEC were exposed to IL-2 (500 to 25,000 U/ml) for 4 h. The steady-state transfer rate of [125I]albumin across the BPAEC monolayer was 3.3 +/- 0.4%/h (n = 10) in control BPAEC (diluent alone), was significantly increased in BPAEC exposed to 500 U/ml of IL-2 (72 +/- 3% above control values, n = 6, P less than 0.02), and further increased in BPAEC exposed to 5,000 U/ml (60 +/- 2% increase above 500 U/ml values, n = 5, P less than 0.02). No further increase was noted after exposure to 25,000 U/ml of IL-2. Additionally, no further increase in [125I]albumin transfer rates was noted in BPAEC exposed to 5,000 U/ml of IL-2 for 24 versus 4 h. Similar changes were found using HAEC. Preincubation of HAEC with an anti-IL-2 low-affinity receptor antibody (anti-IL-2R alpha) inhibited the IL-2-induced permeability increase. Expression of IL-2R alpha receptors in HAEC incubated with 5,000 U/ml of IL-2 for 4 h was also found. Thus, IL-2 appears to have a direct effect on cultural arterial endothelial monolayers not requiring the presence of other cell types or serum proteins. IL-2-induced increases in endothelial macromolecular permeability may play an important role in the pathogenesis of the IL-2-induced vascular leak syndrome seen in vivo.

Most human pulmonary infiltrating lymphocytes display the surface immune phenotype and functional responses of sensitized T cells

Pulmonary infiltrating lymphocytes (PIL) isolated directly from human lung were examined for their surface immune phenotype by monoclonal antibody staining and cytofluorimetry. In order to purify PIL, resected lungs were enzymatically digested with collagenase and DNase and subjected to density centrifugation and nylon-wool column separation. In some cases, CD4+ lymphocytes were further purified with alpha CD8 and complement. The majority of pulmonary lymphocytes were CD2+ (87 +/- 1%) and CD3+ (73 +/- 4%). Virtually all of the CD3+ PIL were Ti alpha beta+. Greater than 90% of both CD4+ or CD8+ PIL were CD45RO+ and CD45RA-, consistent with prior antigen sensitization in vivo. A subset of CD4+ PIL (34 +/- 4%) expressed Leu8, the human congener of the murine MEL-14 lymphocyte homing receptor, whereas most homologous CD4+ peripheral blood lymphocytes were Leu8+ (75 +/- 8; P less than 0.01). HLA-DR surface antigens were expressed by 45 +/- 5% of CD4+ PIL versus 9 +/- 1% of CD4+ peripheral blood lymphocytes (P less than 0.001). There was no significant difference in the percentage of low-affinity interleukin-2 (IL-2) receptor-positive CD4+ lymphocytes in lung and blood (9 +/- 3% versus 13 +/- 2%). Analysis of the DNA synthetic cell cycle showed that approximately 5% of blood CD4+ lymphocytes and approximately 25% of CD4+ PIL were in S/G2/M. Compared to homologous blood T cells, purified PIL displayed enhanced proliferative responses to IL-2 and diminished responses to the lectin phytohemagglutinin. Lectin-stimulated PIL showed greater secretion of interferon-gamma and IL-2 than did blood lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormal intracellular sorting of O-linked carbohydrate-deficient interleukin-2 receptors

The synthesis and intracellular sorting of the interleukin-2 (IL-2) receptor were studied with a line of mutant Chinese hamster ovary (CHO) cells with a reversible defect in protein O glycosylation. Under normal culture conditions the mutant ldlD cannot add N-acetylgalactosamine (Ga1NAc) to proteins. Ga1NAc is the first sugar of mucin-type O-linked oligosaccharides attached to protein. This O-glycosylation defect is rapidly corrected when Ga1NAc is added to the culture mediu. An expression vector for the p55 human IL-2 receptor was transfected into wild-type CHO and ldlD cells and the structure, stability, and cell surface expression of the receptor were examined by immunoprecipitation and antibody-binding assays. Essentially all of the mature form of the normally glycosylated IL-2 receptor in both wild-type CHO cells and ldlD cells incubated with Ga1NAc was expressed on the cell surface. The stability of O-linked carbohydrate-deficient (Od) IL-2 receptors (in ldlD cells without Ga1NAc) was normal; however, missorting of the Od receptors resulted in very little cell surface expression. The sialidase sensitivity and endoglycosidase H resistance of mature Od IL-2 receptors suggest that Od receptor missorting occurred in or beyond the trans Golgi apparatus. The abnormal sorting of the Od IL-2 receptor is compared with the O-glycosylation dependence of the surface expression and stability of the low-density lipoprotein receptor, decay-accelerating factor, and the major antigen envelope protein of Epstein-Barr virus.

Human interleukin-2 anti-idiotypes

We describe the generation of a monoclonal anti-idiotypic (anti-id) antibody directed against affinity purified rabbit antibodies (id) to recombinant human IL-2. This monoclonal antibody, 6A12, has the ability to inhibit the neutralization of IL-2 activity by the id, suggesting that it may bind at or near the IL-2 neutralizing site on the id. 6A12 exhibits IL-2 agonist activity on PHA-activated human T cells. The purified IgG of 6A12 is also shown to bind to a purified soluble recombinant p55 subunit of the IL-2 receptor. Furthermore, purified 6A12 shows inhibition of IL-2 activity in an IL-2 dependent mouse T cell line (CTLL) and this inhibition can be reversed by excess IL-2. These results suggest that although 6A12 may not be an exact 'internal image' of the receptor binding site of IL-2, it may bind to at least the P55 subunit of the ligand binding site on the high affinity IL-2 receptor complex.

Spontaneous expression of the interleukin 2 receptor gene and presence of functional interleukin 2 receptors on T lymphocytes in the blood of individuals with active pulmonary sarcoidosis

Current concepts of the pathogenesis of sarcoidosis suggest that the expanded numbers of activated T-helper/inducer cells at sites of disease activity result, at least in part, from their proliferation in the local milieu. Normal clonal proliferation of T cells involves activation and expression of the IL 2 receptor (IL 2R) gene. Thus, knowing that IL 2R mRNA transcripts are relatively long lived, we hypothesized that sarcoid blood T cells may contain IL 2R mRNA transcripts and express functional surface IL 2R, although the cells are probably activated elsewhere. Northern analysis using a 32P-labeled cDNA probe for the IL 2R p55 protein demonstrated that blood T cells of patients with active sarcoidosis, but not of normal patients, express 3.5- and 1.5-kb IL 2R mRNA transcripts, the same as those observed in normal T cells activated in vitro. Consistent with this, using flow cytometry and an MAb directed against the IL 2R p55 protein (2A3), we observed detectable levels of IL 2R surface protein on increased numbers of blood T cells of active sarcoidosis patients (4.7 +/- 0.9%) compared with blood T cells of normal patients (0.9 +/- 0.2%). Importantly, when the sarcoid blood T cells were exposed to IL 2 in vitro, they proliferated at a rate greater than that of normal blood T cells under the same conditions, suggesting that the IL 2R spontaneously expressed by sarcoid blood T cells were functionally active. In the context of the known compartmentalization of spontaneous IL 2 production and T cell proliferation at sites of disease in active pulmonary sarcoidosis, these IL 2R positive blood T cells would probably have a proliferative advantage if they trafficked to sites of active sarcoidosis, such as the lower respiratory tract.

Expression of functional human interleukin-2 receptors in murine interleukin-3-dependent cells

A murine recombinant retrovirus containing the cDNA encoding the human p55 interleukin-2 (IL2)-binding protein was used to insert this gene into a murine interleukin-3 (IL3)-dependent cell line, FD.C/1. Virus-infected cells, maintained in medium supplemented with IL3, expressed human p55 on the cell surface and readily adapted to growth using human IL2. In the presence of human IL2, the synthesis of the endogenous murine p55 binding protein was induced in FD.C/1 cells, making it difficult to determine whether the human p55 protein was actively involved in the process of growth signal transduction. A cloned cell line, FD.huIL2R-2, was identified which grew in the presence of human IL2 but which had lost the ability to synthesize murine p55 protein. Growth of this clone was inhibited by the monoclonal antibody 2A3 which specifically blocked binding of human IL2 to the human p55 binding protein. Analysis of restriction enzyme digests of FD.huIL2R-2 cell DNA revealed that a rearrangement of a murine p55 gene had occurred, implying that virus infection had resulted in the integration of retroviral DNA at a site close to or within a murine p55 gene. If IL2 signal transduction involves binding to a surface heterodimeric receptor for IL2, it is argued that FD.huIL2R-2 cells contain an IL2 receptor complex of murine p70 and human p55 IL2-binding proteins. Alternatively, it is possible that integration of human p55 DNA into a site close to a murine p55 gene may lead to a hybrid p55 IL2-binding protein. If FD.huIL2R-2 cells express murine p70 IL2-binding protein as part of the receptor complex, the inability of cells to grow in murine IL2 implies that IL2 binding to p70 protein alone is insufficient for a growth signal in these cells. FD.huIL2R-2 cells grow at rates similar in IL3- or human IL2-dependent states. It is likely therefore that the biochemical pathways that control each of these lymphokine-dependent growth states are very similar.

Abnormal intracellular sorting of O-linked carbohydrate-deficient interleukin-2 receptors

The synthesis and intracellular sorting of the interleukin-2 (IL-2) receptor were studied with a line of mutant Chinese hamster ovary (CHO) cells with a reversible defect in protein O glycosylation. Under normal culture conditions the mutant ldlD cannot add N-acetylgalactosamine (Ga1NAc) to proteins. Ga1NAc is the first sugar of mucin-type O-linked oligosaccharides attached to protein. This O-glycosylation defect is rapidly corrected when Ga1NAc is added to the culture mediu. An expression vector for the p55 human IL-2 receptor was transfected into wild-type CHO and ldlD cells and the structure, stability, and cell surface expression of the receptor were examined by immunoprecipitation and antibody-binding assays. Essentially all of the mature form of the normally glycosylated IL-2 receptor in both wild-type CHO cells and ldlD cells incubated with Ga1NAc was expressed on the cell surface. The stability of O-linked carbohydrate-deficient (Od) IL-2 receptors (in ldlD cells without Ga1NAc) was normal; however, missorting of the Od receptors resulted in very little cell surface expression. The sialidase sensitivity and endoglycosidase H resistance of mature Od IL-2 receptors suggest that Od receptor missorting occurred in or beyond the trans Golgi apparatus. The abnormal sorting of the Od IL-2 receptor is compared with the O-glycosylation dependence of the surface expression and stability of the low-density lipoprotein receptor, decay-accelerating factor, and the major antigen envelope protein of Epstein-Barr virus.

Nasal-secretion leukocyte populations determined by flow cytometry during acute rhinovirus infection

Leukocyte populations in the secretions of volunteers challenged by intranasal inoculation with rhinovirus serotype 25 were evaluated by means of flow cytometry. With the light-scatter properties of peripheral blood leukocytes as the standard of reference, significant increases (P less than .05) of both lymphocytes and phagocytes (polymorphonuclear leukocytes plus monocytes) were detected in the nasal secretions of persons infected by the viral challenge. There was a direct correlation of nasopharyngeal symptom severity with both the percentage of lymphocytes (P less than .05) and the percentage of phagocytes (P less than .001). Monoclonal antibodies for specific cell-membrane antigens identified the lymphocytes and phagocytes as leukocytes and also demonstrated the presence of a population of monocytic cells during the phase of maximal symptoms. The panel of monoclonals chosen did not unequivocally identify a lymphocyte population except in the presence of nosebleed. However, the results show that flow cytometry can be used to investigate nasal-secretion cell populations during the rhinovirus common cold.

Anatomy and pathology of the basal ganglia

Neurotransmitters of the basal ganglia are of three types: I, amino acids; II, amines; and III, peptides. The amino acids generally act ionotropically while the amines and peptides generally act metabotropically. There are many examples of neurotransmitter coexistence in basal ganglia neurons. Diseases of the basal ganglia are characterized by selective neuronal degeneration. Lesions of the caudate, putamen, subthalamus and substantia nigra pars compacta occur, respectively, in chorea, dystonia, hemiballismus and parkinsonism. The differing signs and symptoms of these diseases constitute strong evidence of the functions of these various nuclei. Basal ganglia diseases can be of genetic origin, as in Huntington's chorea and Wilson's disease, of infectious origin as in Sydenham's chorea and postencephalitic parkinsonism, or of toxic origin as in MPTP poisoning. Regardless of the etiology, the pathogenesis is often regionally concentrated for reasons that are poorly understood. From studies on Parkinson and Huntington disease brains, evidence is presented that a common feature may be the expression of HLA-DR antigen on reactive microglia in the region where pathological neuronal dropout is occurring.

Characterization of the human B cell stimulatory factor 1 receptor

125I-labeled recombinant human B cell stimulatory factor 1 (BSF-1) was used to characterize receptors specific for this lymphokine on in vitro cell lines representing human B, T, and hematopoietic lineages, as well as on adherent cell lines of epithelial and endothelial origin, and on primary human gingival fibroblasts. BSF-1 binding was extremely rapid and saturable at both 4 and 37 degrees C, with a slow dissociation rate. On all human cell types examined, BSF-1 bound to a single class of high-affinity receptor (less than 3,000 receptors per cell) with a Ka of 0.5-1.0 X 10(10)/M. Human BSF-1 also bound to cell lines of simian but not murine origin. Comparison of kinetic characteristics obtained with a yeast-derived hyperglycosylated form of BSF-1 (Mr 60,000) and N-glycanase-treated, sugar-free BSF-1 (Mr 15,000) showed no significant differences. Among a panel of lymphokines and growth hormones, only unlabeled human BSF-1 was able to compete for the binding of 125I-labeled human BSF-1. Affinity crosslinking experiments resulted in the identification on both Raji cells and on primary human gingival fibroblasts of a receptor subunit with an average Mr of 139,000. These studies show that the BSF-1 receptor on human cells has an extremely broad cellular distribution, while further supporting the notion that the ability of BSF-1 to mediate a spectrum of biological activities cannot be accounted for by overt differences in the receptor for this lymphokine on different cell lineages.

Expression and purification of native human granulocyte-macrophage colony-stimulating factor from an Escherichia coli secretion vector

The human granulocyte-macrophage colony stimulating factor (GM-CSF) was expressed and purified from a high-level Escherichia coli secretion vector. A cDNA fragment encoding mature GM-CSF was fused with the aid of a synthetic oligonucleotide to the E. coli outer membrane signal peptide (ompA) of the secretion expression vector pIN-III-ompA3. The primary construction, designated pLB5001, is under transcriptional control of the tandem lipoprotein promoter (lppP) lactose promoter-operator (lacPO), and is regulated by the lactose repressor. Upon induction, a polypeptide of MW = 14,600 was produced which had GM-CSF activity in a human bone marrow colony assay. The linker sequence between the ompA signal peptide and the amino terminus of the mature GM-CSF was removed by oligonucleotide-directed site-specific mutagenesis to produce GM-CSF with an authentic amino terminus. The resulting construct, designated pLB5001-4, expressed authentic GM-CSF with a specific activity similar to that observed for the pLB5001 specified GM-CSF. Both versions of GM-CSF were associated with the membrane fraction after osmotic shock, and were purified to homogeneity by DEAE-Sephacel chromatography, followed by reversed-phase HPLC. Amino acid sequencing from the amino terminus of the purified GM-CSF established that the ompA signal peptide was cleaved at its normal processing site in both cases.

Expression of genes in cloned murine cell lines that can be maintained in both interleukin 2- and interleukin 3-dependent growth states

Two cloned murine cell lines, FD.C/1 and 32Dcl-23 exhibit switching of lymphokine-dependent growth states. The bone marrow-derived FD.C/1 and 32Dcl-23 cell lines are normally grown in culture medium supplemented with interleukin 3 (IL3). The replacement of IL3 with interleukin 2 (IL2) in the medium results in an increase in IL2 receptor expression in FD.C/1 and 32Dcl-23 cells and the switching of cells to an IL2-dependent growth state. We have compared patterns of protein and phosphoprotein synthesis, as well as the expression of the c-abl, c-ras, c-myb, and c-fos oncogenes in these cell lines maintained in IL3- and IL2-dependent growth states. The synthesis of a series of proteins and phosphoproteins are identified with each of the lymphokine-dependent growth states. All of the oncogenes examined are expressed in both IL2- and IL3-dependent cells and are not altered by phenotypic changes in lymphokine growth dependence. The relationship of oncogene expression to intracellular pathways regulated by lymphokine-receptor interactions is considered.

Interleukin-2 (IL-2) and its receptor

The interleukin-2 (IL-2) receptor system which is responsible for T-cell cycle progression is a unique hormone-receptor system in that both the ligand and the receptor need to be induced. In the present article I will review the biological and molecular characteristics of IL-2 and its receptor, as well as the differential triggering and growth requirements that L3T4+ (T4+) helper and Lyt-2+ (T8+) cytotoxic/suppressor T-cells display to respond. The various mechanisms of regulation operating to restrain clonal IL-2-dependent expansion of normal T-lymphocytes will be discussed.

High level stable expression of human interleukin-2 receptors in mouse cells generates only low affinity interleukin-2 binding sites

A bovine papilloma virus-derived vector was used to direct the high level expression in mouse C127 cells of three different cDNAs encoding the human interleukin-2 receptor. These were: the previously described cDNA clone isolated from the T-cell lymphoma, HUT-102; a cDNA clone isolated from mitogen-activated, normal peripheral blood T cells; and an altered version of the HUT-102 receptor in which Ser247, believed to be the site of protein kinase C-mediated phosphorylation, has been changed to an Ala residue. Fluorescence-activated cell-sorting using a monoclonal antibody directed against the human IL-2 receptor was used to derive stable lines of C127 cells expressing from 2-6 X 10(6) IL-2 binding sites per cell. However, all of these receptors bound IL-2 with low affinity.

Expression of Tac antigen in B cell lymphomas

In a series of 55 cases of B cell derived non-Hodgkin's lymphoma the reactivity of two distinct anti-Tac monoclonal antibodies was examined using a sensitive immunoperoxidase technique on cryostat sections. Eighteen out of the thirty-five cases of B cell lymphomas of low or intermediate grade of malignancy were found to be reactive while six out of 20 cases of high-grade malignancy lymphomas showed a positive immunostaining. No correlation was found between anti-Tac reactivity and surface immunoglobulin phenotype, T65 antigen, or calla expression. These findings showed that IL2 receptor expression is not restricted to activated T cells, and raise the question of the possible role of IL2 in the regulation of malignant B cell clone expansion.

The human interleukin-2 receptor: analysis of structure and function

Considerable information presently exists regarding the molecular, biochemical, and biological features of the human IL-2 receptor. The IL-2 receptor protein, multiple receptor mRNAs, and a single structural gene have now been identified. The important role of this receptor in normal T-cell growth is well established and its potential participation in B-cell growth and differentiation appreciated. The availability of cloned gene products for both the IL-2 receptor and IL-2 may permit the future development of novel biological agents capable of either augmenting or blunting the T-cell immune response. The intriguing interrelationship of HTLV-I and -II infection and altered IL-2 receptor expression is now being unraveled. However, the structural difference in high and low affinity receptors as well as the mechanism by which signals for T-cell growth are propagated through the high affinity receptor remain dominant, unanswered questions in the field.

Detection of lymphokines and lymphokine receptors in pulmonary sarcoidosis. Immunohistologic evidence that inflammatory macrophages express IL-2 receptors

In an investigation of the immunopathogenesis of sarcoidosis, the authors undertook the tissue localization of those lymphokines and lymphokine receptors which are known to play a central role in T-cell and macrophage activation. Using monoclonal antibodies and an ABC immunoperoxidase technique. They determined the distribution of gamma interferon (IFN-g), interleukin-2 (IL-2), and corresponding IL-2 receptors (IL-2R), plus T cells and T cell subsets, B cells, and macrophages within thoracic lymph nodes and lung specimens of 9 patients with active pulmonary sarcoidosis. Epithelioid and multinucleate giant cells within sarcoid granulomas of all specimens showed membrane labeling for IL-2R and IFN-g, in addition to IL-2, suggesting that these cells indeed express functional IL-2 receptors. Infiltrating T cells, largely T4+, were also IL-2R+, and many showed IL-2 and IFN-g labeling. By comparison, macrophages within sections of normal lung or lymph node failed to stain for IL-2, IL-2R, or IFN-g. These immunohistologic studies extend recent in vitro observations by these authors and others that normal human blood monocytes and alveolar macrophages are induced by IFN-g or IL-2 to express functional membrane-bound IL-2 receptors. The in vivo expression of IL-2R by mononuclear phagocytes in pulmonary sarcoidosis is demonstrated, and a new role is suggested for T-cell-derived lymphokines in macrophage activation.

Decreased production of interferon-gamma by human neonatal cells. Intrinsic and regulatory deficiencies

Human neonatal lymphocytes produced little macrophage activation factor in response to mitogens. This correlated with decreased production of interferon-gamma (IFN gamma): adult lymphokines contained 894.2 +/- 177.1 U/ml, whereas neonatal cord and peripheral lymphokines contained 66.9 +/- 17.0 and 116.7 +/- 29.6 U/ml by bioassay. Results by radioimmunoassay (RIA) for IFN gamma were similar. In contrast, the interleukin 2 content of cord lymphokines was greater (P less than 0.01) and that of neonatal peripheral blood lymphokines similar to that of adults. Interleukin 1 production and interleukin 2 receptor expression and affinity were similar for adult and neonatal cells. Interleukins 1 and 2 in amounts comparable to those in adult lymphokines did not increase production of macrophage activation factor or IFN gamma by neonatal cells. Neonatal cells did not contain intracellular IFN or degrade exogenous IFN. Excess suppressor activity was not found in neonatal cultures. Addition of IFN alpha, 10,000-50,000 U/ml of interleukin 2 or phorbol myristate acetate (PMA) to cord mononuclear cells or of adult monocytes or PMA to cord T cells increased IFN gamma production compared to cells stimulated with concanavalin A (ConA) alone. Nevertheless, under optimal conditions (T cells + PMA + Con A), adult cells produced much more IFN gamma (1,360 +/- 261 U/ml by RIA) than cord cells (122 +/- 37 U/ml). Staphylococcal enterotoxin A (SEA) stimulated cord cell IFN gamma production at low cell densities; nevertheless, adult cells produced more IFN in response to SEA 1,341 +/- 350 U/ml) than cord cells (350 +/- 33 U/ml). Decreased production of IFN gamma by neonatal cells appears to be due both to differences in their intrinsic capacity to produce IFN gamma and to differences in regulatory mechanisms.

Induction and upregulation by interleukin 2 of high-affinity interleukin 2 receptors on thymocytes and T cells

We show that purified recombinant interleukin 2 (rIL-2) alone induces the expression of high- and low-affinity interleukin 2 (IL-2) receptors in vitro on human T cells and thymocytes that have not been activated previously by lectins or other inducing agents. IL-2 receptors are expressed after 24 hr, as determined by the binding of 125I-labeled monoclonal anti-IL-2 receptor antibody 2A3, which binds equally to high- and low-affinity receptors. High-affinity receptors were distinguished from low-affinity receptors by the binding of 125I-labeled IL-2 to T cells and by the proliferative response of thymocytes to IL-2, in concentrations that selectively interact with the high-affinity class of IL-2 receptors. The IL-2-induced proliferation of thymocytes in vitro induced by IL-2 alone is dependent upon the concentration of IL-2 and is inhibited by monoclonal anti-Tac antibody, indicating that the proliferative response is mediated by the binding of IL-2 to the receptors. In addition, we demonstrate that IL-2 augments the number of high-affinity receptors on concanavalin A-activated thymocytes. These results document that IL-2 acts as a hormone that induces the activation of thymocytes and T cells, as evidenced by the de novo induction of biologically active, high-affinity IL-2 receptors. IL-2 also upregulates the expression of high-affinity IL-2 receptors on activated thymocytes. These observations illustrate the biologic importance of the regulatory role of IL-2 in the immune response.

Distinct reactivities of four monoclonal antibodies with human interleukin 2 receptor

Two new murine monoclonal IgG1 antibodies, H-31 and H-A26, were characterized in comparison with two previously obtained monoclonal antibodies against human interleukin 2 (IL-2) receptor (IL-2 R), anti-Tac and HIEI. In immunofluorescence assays with various human hematopoietic cells, H-31 and H-A26 antibodies both reacted with only IL-2 R-positive cells, and they precipitated IL-2 R molecules, glycoproteins with molecular weights of 60K and 53K daltons (gp60/gp53), from human T-cell leukemia virus type I (HTLV-I)-carrying MT-2 cells, as demonstrated by sequential immunoprecipitation after absorption of IL-2 R with anti-Tac. Antibody-binding competition assays showed that H-31 and anti-Tac, and H-A26 and HIEI, respectively, competed reciprocally in binding to the cells, and that anti-Tac also inhibited the binding of HIEI but not vice versa. H-31, like anti-Tac, strongly inhibited the IL-2-dependent proliferation of normal activated T-cells, absorption of IL-2 and direct binding of IL-2 to the cells, while H-A26, like HIEI, inhibited those processes only weakly. The spectra of reactivities of these antibodies with various simian cell lines derived by HTLV-I infection were different, as revealed by immunofluorescence studies. Human IL-2 R was shown to express a unique antigenic determinant, detected with HIEI, that was not detectable in IL-2 R molecules of Old and New World monkeys, and also to express determinants common to simian IL-2 R molecules. These observations indicate that H-31 and H-A26 recognize human IL-2 R molecules and that the antigenic sites on the IL-2 R molecule defined by H-31, H-A26, anti-Tac, and HIEI are different.

Interleukin 2 receptor gene expression in normal human T lymphocytes

We have used cDNAs for the human interleukin 2 (IL-2) receptor to study IL-2 receptor gene expression in normal activated T cells. Resting T cells do not contain detectable IL-2 receptor mRNA. Within 1 hr after stimulation with phytohemagglutinin (PHA), a large, presumably nuclear precursor RNA species is seen, which then gradually disappears. Mature IL-2 receptor mRNA forms appear within 8 hr after stimulation, reach peak levels between 8 and 24 hr, and then decline. Thus, in PHA-activated lymphocytes the rise and fall in IL-2 receptor mRNA levels precede by more than 24 hr the peak and decline of IL-2 receptor protein expression occurring at the cell surface. 4 beta-Phorbol 12-myristate 13-acetate (PMA) also stimulates IL-2 receptor mRNA and protein expression by T cells. Combinations of optimal concentrations of PHA and PMA produce an additive effect on IL-2 receptor mRNA levels, suggesting that PHA and PMA may induce IL-2 receptor gene expression through different, complementary mechanisms. Nuclease S1-protection assays indicate that IL-2 receptor mRNAs may differ in length due to the use of three different polyadenylylation signals. Further, these assays demonstrate the presence of transcripts that lack a 216-base segment within the protein-coding region and thus do not encode a functional IL-2 receptor. Nuclear transcription assays indicate that the increase in IL-2 receptor mRNA is reflected at the level of transcription. Thus, IL-2 receptor gene regulation controls IL-2 receptor expression at the cell surface and is intimately linked to the control of T-cell proliferation.

Stable expression of cDNA encoding the human interleukin 2 receptor in eukaryotic cells

Human interleukin 2 (IL-2) receptor cDNA derived from HUT 102B2 cells was stably expressed in murine L cells. These L cell transfectants (a) displayed surface receptors of the aberrant size of the IL-2 receptors on HUT 102B2 cells, (b) did not respond to exogenous IL-2 with augmented proliferation, and (c) expressed low affinity but not high affinity receptors for IL-2.

Cloning, sequence and expression of human interleukin-2 receptor

T lymphocytes, essential for the generation of a normal immune response, require the presence of the lymphokine interleukin-2 (IL-2) in order to proliferate. Cells that respond to IL-2 possess a surface receptor glycoprotein specific for this lymphokine. We have recently purified and chemically characterized the IL-2 receptor from both phytohaemagglutinin-activated human T cells and the human T-cell lymphoma HUT-102 (ref. 5). From the NH2-terminal protein sequence obtained in that study, we have now used synthetic oligonucleotides to probe a complementary DNA library, prepared from HUT-102 messenger RNA, for the presence of cDNA clones that might code for the IL-2 receptor. Two cDNA clones were isolated which had closely related DNA sequences. Interestingly, only one coded for an active receptor when transfected into COS-7 cells. This clone contained a 216-base pair (bp) insert that was not present in the other clone. The insert was flanked by an 8-bp direct repeat reminiscent of a transposable element, and appeared to code for a region of marked structural homology to the NH2-terminal region of the receptor molecule.