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

The Role of Chemokine IL-7 in Tumor and Its Potential Antitumor Immunity

Interleukin-7 (IL-7) is a cytokine belonging to the chemokine family. It plays a key role in the differentiation, development, and maturation of T lymphocytes and B lymphocytes, which is pivotal to adaptive immunity. In addition to its role in lymphocyte development, recent studies have indicated the antitumor functions of IL-7 in the tumor microenvironment. In this review, we discuss the role of IL-7 in tumors and summarize its antitumor potential and clinical application in lymphoma, leukemia, breast cancer, colon cancer, and so on. Furthermore, the combinational strategies of IL-7 and other antitumor drugs have been also discussed.

Interleukin-2 as immunotherapeutic in the autoimmune diseases

Interleukins, also called cytokines are secretory proteins that bind to specific receptors and play a critical role in the intercellular communication between cells of the immune system. Cytokines are mainly produced by T lymphocytes, macrophages and eosinophils. Among its functions are the activation and suppression of immune system responses, induction of cell division and regulation of memory cells. Interleukin 2 (IL-2) is a secretory monomeric glycoprotein composed of 149 amino acids containing a signal peptide of 20 amino acids. It is classified as a member of the type I cytokines family. IL-2 binds to its receptor (IL-2R receptor) with high affinity and its signaling function promotes the activation of various subtypes of lymphocytes during the process of cell differentiation to generate an immune or homeostatic response. The specificity of IL-2 depends on its binding to low, medium or high-affinity receptors. Interleukin 2 acts as a regulator of the proliferation of CD4+ and CD8+ T cells. There is a relationship between IL-2 and autoimmune diseases due to its influence in the differentiation of T helper cells, which in turn directly influence immunological response processes. Therefore, IL-2 is a key element in the control and treatment of those diseases. In recent years, many therapeutic agents based on biomolecules and recombinant chimeric proteins have been developed to treat different autoimmune diseases. In this review, we focus on the use of interleukin 2 as a versatile therapeutic agent, alone or associated with other molecules to increase the efficiency of autoimmune disease treatment.

Detection of salivary interleukin-2 in recurrent aphthous stomatitis

OBJECTIVE

The present study was undertaken to estimate and compare salivary interleukin-2 (IL-2) levels in patients with recurrent aphthous stomatitis, among healthy controls and their variation with age and sex.

STUDY DESIGN

Saliva was collected from 60 patients within the age range of 16-60 years which included 30 patients (17 Females and 13 Males) with recurrent aphthous stomatitis and healthy control group consisted of 30 participants (18 Females and 12 Males). IL-2 estimation was done in both the groups using enzyme linked immunosorbent assay (ELISA). Statistical analysis of the data was done using Independent 't' test.

RESULTS

The results showed increased salivary IL-2 levels in patients with recurrent aphthous stomatitis compared to the healthy controls. The IL-2 levels were also increased in patients with the age group of 16-30 years compared to other age groups. Similar increase of IL-2 was also seen in female patients.

CONCLUSION

Age related and sex related alterations of IL-2 in recurrent aphthous stomatitis patients were observed.

Small-molecule inhibitors of IL-2/IL-2R: lessons learned and applied

The IL-2:IL-2R protein-protein interaction is of central importance to both healthy and diseased immune responses, and is one of the earliest examples of successful small-molecule inhibitor discovery against this target class. Drug-like inhibitors of IL-2 have been identified through a combination of fragment discovery, structure-based design, and medicinal chemistry; this discovery approach illustrates the importance of using a diverse range of complementary screening methods and analytical tools to achieve a comprehensive understanding of molecular recognition. The IL-2 story also provides insight into the dynamic nature of protein-protein interaction surfaces, their potential druggability, and the physical and chemical properties of effective small-molecule ligands. These lessons, from IL-2 and similar discovery programs, underscore an increasing awareness of the principles governing the development of drugs for protein-protein interactions.

Neural precursors attenuate autoimmune encephalomyelitis by peripheral immunosuppression

OBJECTIVE

Intracerebroventricular or intravenous (IV) injection of neural precursor cells (NPCs) attenuates experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis. Although stem cell therapy was introduced initially for cell replacement, we examine here whether NPCs possess immunomodulatory effects.

METHODS

We examined the effects of systemic administration of NPCs on central nervous system (CNS) inflammation in EAE and the interactions between NPCs and T cells in vitro and in vivo.

RESULTS

IV NPC therapy decreased significantly CNS inflammation and tissue injury and attenuated the clinical severity of EAE. IV-injected NPCs could not be found in the CNS but were detected in lymphoid organs. Coculture experiments showed that NPCs inhibited the activation and proliferation of lymph node-derived T cells in response to CNS-derived antigens and to nonspecific polyclonal stimuli. The relevance of NPC/lymph node cell interactions in vivo was further demonstrated when lymph node cells obtained from IV NPC-treated mice exhibited poor encephalitogenicity on transfer to naive mice and caused a markedly milder EAE compared with those obtained from nontreated mice.

INTERPRETATION

IV administration of neural precursors inhibits EAE by a peripheral immunosuppressive effect. Our findings suggest a profound bystander inhibitory effect of NPCs on T-cell activation and proliferation in the lymph nodes, leading to amelioration of EAE.

Immunostimulatory effects of the anionic alkali mineral complex Barodon on equine lymphocytes

Previous studies have shown that the anionic alkali mineral complex BARODON has an immunoenhancing effect on pigs as an adjuvant and as a nonspecific immunostimulant. Likewise, the equine immune system has been defined with various monoclonal antibodies specific to equine leukocyte differentiation antigens to determine the possibility of enhancing equine resistance to respiratory diseases and promoting other immunostimulatory effects with the application of BARODON. Compared with the control group, after 3 weeks of treatment, BARODON-treated groups showed higher proportions of cells (P < 0.05) expressing major histocompatibility complex class II and CD2, CD4(+), CD4(+) CD25(+), CD8(+), and CD8(+) CD25(+) T lymphocytes, dendritic cells, and surface immunoglobulin M(+) B lymphocytes in peripheral blood, as well as enhanced cell proliferative responses with phytohemagglutinin and increased phagocytic activity against Streptococcus equi and Staphylococcus aureus strains with high antibiotic resistance, the bacteria frequently identified as etiologic agents of equine respiratory diseases at the Seoul Race Park in Seoul, Korea. This study shows that BARODON may act as an immunostimulator and can be an effective alternative to antimicrobial feed additives for nonspecific improvements in equine immune responses, particularly against respiratory diseases.

Differential effect of sodium arsenite during the activation of human CD4+ and CD8+ T lymphocytes

Contamination of water with arsenic is a problem affecting several regions of the world. Peripheral blood mononuclear cells (PBMC) from chronically exposed individuals show a lower replicating activity than non-exposed individuals when stimulated with phytohemagglutinin (PHA). We have previously reported that PBMC from healthy donors treated in vitro with 1 muM sodium arsenite (NaAsO2) and stimulated with PHA showed a reduction in proliferation by a delay in cell cycle entry and a decrease in the rounds of cell division. In this paper we tested the effect of 1-5 muM NaAsO2 on the proliferation, viability, blast transformation, expression of the CD4 and CD8 molecules, and during the activation and proliferation of both CD4+ and CD8+ T lymphocytes. We found a reduction in cell proliferation and an increase in non-dividing cells with higher concentrations of NaAsO2 (2-5 microM) when proliferation was studied by 5,6-carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution. The use of 7-aminoactinomycin D (7-AAD) in CFSE-labeled cells allowed us to detect an increase in percentage of non-dividing cells, and an increase in apoptotic/dead cells mainly in non-proliferating cells. Analysis of the expression of CD4 and CD8 molecules on these cells showed that concentrations > or = 2 microM NaAsO2 reduced the expression of the CD8 molecule and induced apoptosis/death in CD4+ cells. Analysis of blast transformation by flow cytometry showed an accumulation of CD8+ resting cells in the presence of NaAsO2. Analysis of CD25 and CD69 expression in kinetics experiments in both subtypes showed a delay in the expression of CD25 and a delay in the downregulation of the CD69 molecule, in both CD4+ and CD8+ cells. However, in the case of CD8+ cells, we detected an accumulation of a CD25- CD69- population in the presence of increasing concentrations of NaAsO2. Altogether, our results show that NaAsO2 alters the expression kinetics of the early activation molecules CD25 and CD69 similarly in both subtypes. In addition, activated and non-activated CD4+ cells die by apoptotic mechanisms and although a percentage of CD8+ cells also die by apoptosis, a subpopulation of these cells is unable to activate and thus accumulates as resting cells.

The effect of aging on T cell responses in the horse

Horses greater than 20 years of age exhibit alterations in their immune responses similar to those observed in other aged individuals. The purpose of this study was to characterize immunosenescence in a population of aged ponies. The peripheral blood mononuclear cells (PBMC) from aged ponies exhibited a decreased proliferative response to various mitogens that was not overcome by the addition of interleukin 2 (IL-2) to the cultures. No difference in overall expression of the IL-2 receptor was seen between young and aged ponies, though CD8(+) cells from aged ponies exhibited increased levels of IL-2 receptor expression. The kinetics of the response to both mitogen and IL-2 did not appear to be affected in the aged PBMCs. These results indicate that the age-related decrease in the proliferative response to mitogens is not due to a failure to produce or respond to IL-2 but probably involves some other process.

The synthetic peptide related to the central part of human interleukin-2 molecule accelerates growth and vascularization of sarcoma 180 in mice

The synthetic peptide C-1-6 related to the central part of human interleukin 2 molecule (sequence 59-72; N- and C-modified) had been shown previously to inhibit cytotoxic activity of macrophages converting them to synthesis of growth factors. In this paper the effect of C-1-6 on growth of sarcoma 180 in mice was studied. C-1-6 significantly accelerated tumor growth having been injected into mice in dose 5 or 50 microg per animal since the 4th day after tumor cells transplantation. Supernatants of Mphi in vitro activated by C-1-6 (10 microg/ml) and injected into mice also accelerated significantly sarcoma mass diurnal increasing as compared to mice treated with supernatants of non-activated Mphi or activated with bacterial lipopolysaccharide. A single injection of C-1-6 into mice either at the day or at the next day of tumor cells inoculation increased significantly the number of vessels growing up to transplant, thus the forming of the vascular bed had preceded tumor volume enlargement.

IL-2, its receptors, and bcl-2 and bax genes in normal, hyperplastic and carcinomatous human prostates: immunohistochemical comparative analysis

The presence of interleukin-2 (IL-2) and its receptors (Ralpha, Rbeta, Rgamma), and their relationship with the products of bcl-2 and bax genes was studied in normal prostates, benign prostatic hyperplasia (BPH), and prostatic cancer (PC) by ELISA, Western blot, and immunohistochemistry. A comparative semiquantitative immunohistochemical study was also performed. For all the antibodies assayed, immunoreactions were found in the epithelium and some stromal cells in the three types of specimens studied. These immunoreactions were much more higher in PC samples than in normal prostates. In BPH, immunoreactions were similar to that of normal prostates (bax), similar to that of PC (IL-2 and its three receptors), or intermediate between that of normal prostates and that of PC (bcl-2). Immunoexpressions of IL-2 and its receptors were found in the epithelial basal cells and some stromal cell of normal prostates and might be related to the control of the proliferation-apoptosis equilibrium. The increased expressions of IL-2 and its receptors in the epithelium of prostates in BPH, associated with increased bcl-2 expression which would account for the decrease in the apoptosis index that has been reported in this disorder. The increased expression of both bcl-2 and bax in PC might be involved in the higher apoptosis index reported in PC specimens. Since IL-2 administration seems to have an anti-tumour effect, the increased expression of this interleukin in BPH and PC could be interpreted as an attempt to hinder cell proliferation which would only be efficient at high doses.

Serum soluble interleukin-2 receptor: a useful indicator of the clinical course in pulmonary tuberculosis

SETTING

In tuberculosis both host protection and most pathogenic mechanisms depend on T lymphocytes. After activation by mycobacterial antigens, T cells both secrete interleukin-2 (IL-2) and express a high affinity receptor for this molecule (IL-2R) on their own surface. A soluble fraction of IL-2 receptor (sIL-2R), released from cell membrane, is detectable in serum and its concentration is known to be elevated in tuberculosis.

OBJECTIVE

To ascertain the role of sIL-2R as an indicator of clinical evolution and response to antituberculosis treatment.

DESIGN

A prospective study, in which we have measured serum sIL-2R in 52 patients (42 with active and 10 with inactive pulmonary tuberculosis) and in 36 healthy controls. In 20 patients, serum sIL-2R levels were measured serially throughout the treatment. Levels of sIL-2R were correlated to clinical and radiological parameters.

RESULTS

Serum sIL-2R was significantly increased in patients with tuberculosis as compared to healthy subjects. Both the radiological findings and the clinical state of patients showed a good correlation with sIL-2R. All patients with normal values of sIL-2R 6 months after starting therapy had a favourable clinical evolution.

CONCLUSION

Serum sIL-2R is a useful marker of the clinical state and evolution of patients with pulmonary tuberculosis. The detection of permanently high values beyond 3-6 months of treatment suggests that additional drugs or prolonged administration would be advisable in order to ensure full recovery.

Expression of the mouse interleukin-2 receptor gamma chain in various cell populations of the thymus and spleen

Expression of the gamma chain, which is shared among functional receptor complexes for interleukin (IL)-2, IL-4 and IL-7, was examined with hematopoietic cells in mouse thymus and spleen by flow cytometry. The gamma chain was expressed in cell populations from the spleen. Stimulation with concanavalin A and lipopolysaccharide caused fluctuation in expression of the gamma chain in T and B cells, respectively. T lineage cells developing in the adult thymus expressed the gamma chain. Fetal thymus at day 15 contained mostly immature thymocytes, which also expressed the gamma chain. These results demonstrate that the gamma chains is widely expressed in T lineage cells, probably indicating that the gamma chain plays a role not only in the proliferation of mature hematopoietic cells but also in the development of immature cells through signal transduction as a common receptor subunit for multiple cytokines.

Effect of triiodothyronine and in vitro growth hormone on avian interleukin-2

One-day-old chickens were treated with varying levels of triiodothyronine (T3) added to the diet. At 28 days of age, the IL-2-like activity in the splenocyte culture supernatants were assessed. The lowest dose of T3 (0.1 ppm) enhanced IL-2-like activity while the highest dose (1.0 ppm) was significantly suppressive. The intermediate dose elicited varying effects. Recombinant chicken growth hormone (rcGH) was added to some cultures 24 h prior to IL-2 assay. In vitro rcGH significantly depressed the IL-2-like activity of splenocytes from animals given the low T3 diet. The addition of varying concentrations of T3 in vitro to splenocytes from non-T3-supplemented chickens had no effect on the IL-2-like activity. These results indicate that in vivo supplementation of low dietary T3 but not in vitro T3 is effective in enhancing avian IL-2-like activity. The addition of rcGH in vitro can modify this response.

Thyroid function and thyroid autoimmunity independently modulate serum concentration of soluble interleukin 2 (IL-2) receptor (sIL-2R) in thyroid diseases

OBJECTIVE

The serum concentration of soluble interleukin-2 receptor (sIL-2R) is a marker of T-lymphocyte activation. Increased circulating sIL-2R has been reported in untreated Graves' disease. This finding has been interpreted as the consequence of the autoimmune activation, but recent data suggest that sIL-2R is directly correlated to thyroid state. The aim of this study was to elucidate the respective roles of autoimmunity and thyroid function in modulating serum sIL-2R.

DESIGN AND PATIENTS

sIL-2R was evaluated in 20 normal euthyroid subjects and in a large series of patients with autoimmune and non-autoimmune thyroid disorders in different functional state.

MEASUREMENTS

sIL-2R was assayed by a solid-phase monoclonal antibody assisted ELISA method.

RESULTS

Serum sIL-2R in normals was 461 +/- 186 U/ml (mean +/- SD). Increased sIL-2R was found in 61 hyperthyroid patients with Graves' disease (1610 +/- 962 U/ml, P < 0.0001) and in 23 with toxic adenoma (1121 +/- 598 U/ml, P < 0.0001). Restoration of euthyroidism lowered to normal sIL-2R in both groups. Serum sIL-2R was higher in euthyroid Graves' disease patients with active than in those with non-active ophthalmopathy. Decreased serum sIL-2R (228 +/- 93 U/ml, P < 0.0001) was found in 30 patients hypothyroid after total thyroidectomy. Highly variable circulating sIL-2R (range 100-1456 U/ml, mean +/- SD: 379 +/- 301 U/ml) was found in 49 patients with hypothyroid Hashimoto's thyroiditis (P = NS vs normals; P < 0.02 vs post-thyroidectomy hypothyroid patients). Treatment with L-thyroxine increased sIL-2R in all thyroidectomized and in the majority of Hashimoto's thyroiditis patients. In individual Hashimoto's thyroiditis patients (mostly with increased serum sIL-2R), L-thyroxine caused a decrease of circulating sIL-2R, sIL-2R was normal in 29 patients with euthyroid Hashimoto's thyroiditis. Both in Graves' disease and in Hashimoto's thyroiditis, no correlation was found between sIL-2R and anti-thyroglobulin, anti-thyroid peroxidase and anti-thyrotrophin-receptor autoantibodies. Highly significant positive correlation between serum thyroid hormones and sIL-2R was found in all study groups.

CONCLUSIONS

In thyroid disorders thyroid hormones are the main regulator of serum sIL-2R concentration. The contribution of autoimmune activation may be detected only in some patients with autoimmune hypothyroidism, while in Graves' disease the role of the immune system is masked by the hyperthyroid state.

Effects of lymphocyte activation on transfer RNAs

The influences of mitogen activation on the functional capacity of rat splenic tRNAs were evaluated. The specific amino acid acceptor activity, pmol of a specific amino acid accepted per nmol of tRNA, of isolated splenic tRNAs from in vivo Concanavalin A (37 h)-treated rats were up to 8 times the specific amino acid acceptor activities of splenic tRNAs from control rats. Control splenic tRNAs were treated with purified liver tRNA nucleotidyltransferase in vitro to repair the 3'[CCA] terminus of tRNAs, and subsequently assayed in an aminoacylation reaction. The specific amino acid acceptor activities were slightly increased over those tRNAs not repaired with tRNA nucleotidyltransferase, indicating the presence of a low level of defective but repairable tRNAs in the control rat spleen. Furthermore, our results indicate that cyclosporin A (inhibitor of lymphocyte activation) blocks the Concanavalin A stimulation of tRNA charging ranging from 16 to 93%.

Circulating soluble interleukin 2 receptor concentration is increased in both immunogenic and nonimmunogenic hyperthyroidism

High serum concentration of soluble interleukin-2 receptor (sIL-2R) is considered a reliable marker of T lymphocyte activation. It has been recently reported that sIL-2R levels are increased in untreated Graves' disease. This finding has been interpreted as the consequence of an active autoimmune state, but the relevance of the thyroid function per se was not investigated. In the present study we assayed sIL-2R by ELISA in 20 normal subjects and in a series of patients with immunogenic (Graves' disease, GD) or nonimmunogenic (toxic adenoma, TA) hyperthyroidism. Significant increased concentrations of sIL-2R were found in 46 patients with untreated hyperthyroid GD (mean +/- SD: 1,683 +/- 1016 U/ml, vs 461 +/- 186 U/ml in normal controls, p less than 0.0001) and in 21 with untreated TA (1,111 +/- 617 U/ml, p less than 0.0001 vs normals). Restoration of the euthyroid state by antithyroid drugs or 131I administration was associated with a normalization of sIL-2R (516 +/- 174 U/ml in 38 patients with GD and 365 +/- 90 U/ml in 12 with TA; p = NS vs normals and p less than 0.001 vs the untreated state for both groups). A highly significant positive correlation between serum sIL-2R and free triiodothyronine (FT3) (r = 0.724, p less than 0.0001) or free thyroxine (FT4) (r = 0.698, p less than 0.0001) concentrations was found in combined sera obtained from all untreated and treated patients, irrespectively of the autoimmune or nonautoimmune nature of the underlying hyperthyroid disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation of an interleukin 2-binding receptor from activated lymphocytes by high-performance immunoaffinity chromatography

Isolation of a lymphokine-binding receptor, from activated lymphocyte membranes, can be achieved by high-performance immunoaffinity chromatography (HPIAC), using immobilized antibodies against human interleukin 2 (IL-2), as the ligand and natural IL-2 as the receptor probe. Activated lymphocytes were reacted with IL-2, sonically disrupted and their membranes solubilized, prior to passage through the HPIAC column. The IL-2 acted as an efficient receptor probe, which helped to maintain the integrity of the receptor during the isolation procedure and also acted as an attachment antigen for the immunoaffinity ligand. Recovery of the bound receptor was achieved by dissociation of the receptor-antigen-immobilized ligand complex by the action of chaotropic ions and collection of the released receptor from the column effluent during the elution phase of the separation.

A bidirectional regulatory network involving IL 2 and IL 4 in the alternative CD2 pathway of T cell activation

In this study we examined the effect of interleukin 4 (IL 4) on T cell activation and proliferation via the alternative CD2 pathway. To this end highly purified human resting T cells were cultured with a stimulating pair of anti-CD2 monoclonal antibodies in the absence of accessory signals from monocytes. Addition of either recombinant (r)IL 2 or rIL 4 resulted in proliferation of the anti-CD2-stimulated T cells. The growth-promoting effect of rIL 4 on preactivated. T cells was shown to be partly a direct effect. rIL 4 also induced IL 2 production and, as a consequence, the effect of rIL 4 on T cell growth was enhanced by endogenously produced IL 2. Moreover, rIL 4 acted in synergy with exogenously added rIL 2 in promoting growth of anti-CD2-stimulated T cells. The synergistic effect of IL 2 and IL 4 could be explained by IL 2-induced up-regulation of IL 4 responsiveness. In contrast, preincubation with rIL 4 did not enhance IL 2 responsiveness and rIL 2 but not rIL 4 up-regulated IL 2R expression on anti-CD2-stimulated T cells. Finally we could demonstrate that monocyte-produced cytokines (IL 1 and IL 6) enhance the proliferative response to rIL 4 of anti-CD2-stimulated T cells. It can be concluded that IL 4 can act as a paracrine growth factor for T cells activated in the alternative CD2 pathway, and that it acts synergistically with IL 2, IL 1 and IL 6. Moreover, IL 4 is a helper signal for IL 2 production. Thus, IL 2 and IL 4 are involved in a bidirectional regulatory network, with IL 4 as an inducer of IL 2 production, and IL 2 as an enhancer of IL 4 responsiveness.

High-affinity receptors for interleukin-2 are not required for the induction of human unstimulated B lymphocyte differentiation by this lymphokine

We have reported that one of the currently known receptors for interleukin-2 (IL-2), the p70 protein, is constitutively expressed on resting T lymphocyte membrane. We demonstrated that exposure of these cells to high concentrations of IL-2 resulted in the transcription of genes whose expression occurred early during cell activation such as cmyc, cmyb protooncogenes, and the Tac gene itself. IL-2 is thought to exert its biological effects by binding to its high-affinity receptors on cell membrane. Recent studies using B cell lines emphasized that within the high-affinity receptor complexes, p55 serves to allow high-affinity binding, and p70, to transduce signals. In this study, we prepared human unstimulated B cells devoid of detectable Tac antigen, and consequently, of the high-affinity receptor complexes. We designed experiments such that no in vitro de novo expressed receptors, if any, could interact with IL-2, so that any biologic events triggered by IL-2 must have been mediated in the absence of the high-affinity receptors. Under these conditions, we demonstrated that a short and unique exposure (1 hr) of these cells to high concentrations (5 nM) of IL-2 allowed its binding to cell membrane and resulted in a competent signal leading to the generation of a majority of 25S Tac mRNA, and a progression signal allowing B cell terminal differentiation into plasma cells.

Modulation of the interleukin 2 receptor by maternal and cord blood serum

In this report, the potential inhibitive action, of maternal serum (retroplacental and peripheral), and cord blood serum on the expression of the Il2r has been studied. Calf and male serum were used as a control. In order to have an optimal Il2r expression, a previous PHA cellular stimulation was performed. The maternal serum's Il2r inhibitive property was measured during and after the pregnant period. The presence of Il2r on maternal lymphocytes, cord blood cells, and unrelated donor mononuclear cells has been investigated (after a PHA stimulation assay). The downregulated Il2r expression of neoplastic cell line (Hut78 cell line) under the influence of maternal serum has been observed. The examination of the inhibitive action due to maternal serum has suggested that a factor included in the IgG fraction is mainly responsible for the downregulating property concerning the Il2r expression. A possible mechanism for the action of this factor has been studied. Further experiments suggest that the addition of recombinant Il2 during the action of low doses of maternal IgG allows a partial reexpression of the Il2 receptor. However, at physiological concentrations of IgG, the Interleukin 2 receptor downregulation becomes irreversible.

Isolation of a specific membrane protein by immunoaffinity chromatography with biotinylated antibodies immobilized on avidin-coated glass beads

Avidin-coated, solid glass beads have been used as an immobilization support for attaching biotinylated antibodies. These beads have been packed into analytical, semi-preparative and preparative columns and used to isolate the B27 histocompatibility anigen (HLA) from human lymphocytes. The beads provided a suitable column material for all three chromatographic procedures and, depending on the size of the immunoaffinity column, B27 antigen could be isolated in nanogram to microgram quantities. Polyacrylamide gel electrophoresis demonstrated the presence of only a single band in the immunoaffinity peaks isolated by all three procedures. Enzyme-linked immunosorbent assay analysis of these immunoaffinity-isolated materials revealed that they were biologically active and could be used to determine the levels of anti-B27 antibodies in clinical studies.

NF-kappa B protein purification from bovine spleen: nucleotide stimulation and binding site specificity

The activity of the enhancer for the kappa immunoglobulin light chain gene critically depends on the presence in the nucleus of the NF-kappa B protein. We purified NF-kappa B over 50,000-fold and identified two protein species, 42 and 44 kDa, that could be eluted and renatured from a sodium dodecyl sulfate/polyacrylamide gel to give specific DNA-binding activity. Binding of the purified bovine NF-kappa B as well as that from human and murine B- or T-lymphoid cell extracts was dramatically stimulated by nucleoside triphosphates. This effect distinguished NF-kappa B from a related factor, H2-TF1. Purified NF-kappa B interacted efficiently with regulatory sequences that function during either B- or T-lymphocyte activation, including the human immunodeficiency virus enhancer and a NF-kappa B binding site we detected in the interleukin 2 enhancer.

High-affinity interleukin-2 receptors on blood lymphocytes are decreased during active rheumatoid arthritis

The expression of receptors for interleukin-2 (IL-2R) was examined in patients with active or inactive rheumatoid arthritis (RA) and in control subjects. Unstimulated blood lymphocytes from patients with active RA had increased levels of total IL-2R, as measured by Tac-positive cells, compared with the levels found in the other 2 groups. Mitogen-stimulated cells from patients with active RA expressed less IL-2R per cell, but the most striking feature was the failure to express high-affinity IL-2R. These changes could reflect persistent antigenic stimulation and explain the defective cell-mediated immunity in RA patients.

Mitogen and lymphokine stimulation of heat shock proteins in T lymphocytes

We have examined the effects of phytohemagglutinin (PHA) and the polypeptide growth factor interleukin 2 (IL-2) on the synthesis of the 70- and 90-kDa heat shock proteins (HSP70 and HSP90, respectively) in human T lymphocytes. Resting T cells (G0) stimulated with PHA responded with a generalized increase in protein synthesis that included HSP70. Gel blot analysis indicated that steady-state levels of HSP70 mRNA were not specifically modulated by PHA. Synthesis of HSP90 protein, however, peaked very rapidly following PHA stimulation and decreased sharply after 1 hr. When IL-2-dependent human T cells, synchronized by IL-2 deprivation, were treated with IL-2, synthesis of HSP70 mRNA was increased as much as 15-fold. HSP70 and HSP90 protein synthesis increased significantly upon IL-2 stimulation of human T lymphocytes. Two distinct members of the ancient family of heat shock genes, HSP70 and HSP90, are shown to be stimulated at the activation and progression stages of lymphocyte mitogenesis, which suggests that genetic mechanisms evolved from primitive stress/adaptation responses may be conserved in mammalian cellular activation.

A modified in situ enzyme-linked immunosorbent assay for quantitating interleukin-2 activity employing monoclonal anti-IL-2 receptor antibody

The IL-2R ELISA recently described by Igietseme and Herscowitz (J. Immunol. Methods 97 (1987) 123) is a simple and reliable procedure for measuring the immunological activation of lymphocytes based on the expression of the early activation antigen, the interleukin-2 receptor (IL-2R). In the present report, this assay has now been adapted for the quantitation of IL-2 in culture supernatants and is based on the measurement of augmentation of IL-2R expression resulting from the exposure of sensitive cells (IL-2-dependent T cell line, CTLL-2, and mitogenic blasts) to IL-2. Under the conditions of these experiments, the magnitude of IL-2R expression appears to be directly proportional to the concentration of IL-2 in a given sample up to an optimum concentration beyond which no further increase in IL-2R expression is observed. Dose-response curves revealed that the assay correlates well with the proliferative response of the responder cells as measured by the [3H]thymidine (3H-TdR) uptake assay which is the commonly employed assay for quantitating IL-2. Using a simple mathematical formula, units of IL-2 activity could be assigned to unknown IL-2 preparations employed in these studies based on the activity contained in a standard IL-2 preparation. In an attempt to further simplify the procedure, a novel approach involving an in situ assay was designed and was found to be applicable for quantitating IL-2 by both the 3H-TdR uptake assay and the IL-2R ELISA. The assay can provide direct information about the immediate effect(s) of ligand-to-receptor binding and/or the effect(s) of ligand on the initial response of the cell. The assay could be adapted to quantitate the interleukins, in general.

Expression of platelet-derived growth factor receptors is induced on connective tissue cells during chronic synovial inflammation

The tissue distribution of the receptor for platelet-derived growth factor (PDGF) was investigated by immunohistochemistry on frozen sections from normal and inflamed synovial tissue using monoclonal antibodies to the receptor. Non-inflamed synovial tissue showed no staining, indicating that PDGF receptor expression is low or absent in normal tissue. In contrast, tissue from synovitis with prominent neovascularization showed a strong staining in the tunica media of the proliferating blood vessels as well as on connective tissue cells in the stroma. Tissue from synovitis with prominent proliferation of synovial lining showed intense staining for PDGF receptors in fibroblast-like cells of the lining and a less intense staining on vascular and connective tissue cells deeper in the stroma. Staining for PDGF receptors was also intense in the pannus tissue close to infiltrated bone and cartilage. In all these forms of synovitis, PDGF receptor staining was associated with increased HLA-DR staining and infiltration of macrophages and T lymphocytes. The finding that PDGF receptor expression is induced in conjunction with the chronic synovial inflammation associated with rheumatoid arthritis and some other forms of arthritides suggests that PDGF may play a role in the stimulation of mesenchymal cell proliferation that often accompanies chronic inflammatory disease.

Downregulation of L3T4+ cytotoxic T lymphocytes by interleukin-2

Proliferation of activated cytotoxic T lymphocytes (CTLs) that recognize foreign histocompatibility antigens is induced by interleukin-2, a potent immunoregulatory molecule originally described as T cell growth factor. Interleukin-2 (IL-2) is widely used to isolate and induce clonal expansion of CTLs for functional studies in vitro and in vivo. However, in studies with CTLs specific for class I and class II histocompatibility antigens, IL-2 rapidly downregulated the lytic activity of some class II-specific CTLs in a time- and dose-dependent manner. Lytic activity of L3T4+ CTLs specific for the murine class II antigen I-Ek was repeatedly up- and downregulated in vitro by alternate exposure to specific (alloantigen) and nonspecific (recombinant IL-2) signals, respectively. These results demonstrate that some CTLs modulate their functional property (cytolysis) while undergoing IL-2-driven cell proliferation without loss of antigen specificity or ability to revert to a lytic phenotype.