T cells responsive to myelin basic protein in patients with multiple sclerosis.

Gene mutation in vivo in human T lymphocytes appears to occur preferentially in dividing cells. Individuals with multiple sclerosis (MS) are assumed to have one or more populations of diving T cells that are being stimulated by autoantigens. Mutant T cell clones from MS patients were isolated and tested for reactivity to myelin basic protein, an antigen that is thought to participate in the induction of the disease. The hypoxanthine guanine phosphoribosyltransferase (hprt) clonal assay was used to determine mutant frequency values in MS patients with chronic progressive disease. Eleven of 258 thioguanine-resistant (hprt-) T cell clones from five of the six MS patients who were tested proliferated in response to human myelin basic protein without prior in vitro exposure to this antigen. No wild-type clones from these patients, nor any hprt- or wild-type clones from three healthy individuals responded to myelin basic protein. Thus, T cell clones that react with myelin basic protein can be isolated from the peripheral blood of MS patients.

Homologies between T cell receptor junctional sequences unique to multiple sclerosis and T cells mediating experimental allergic encephalomyelitis.

The selection of T cell clones with mutations in the hypoxanthine guanine phosphoribosyltransferase (hprt) gene has been used to isolate T cells reactive to myelin basic protein (MBP) in patients with multiple sclerosis (MS). These T cell clones are activated in vivo, and are not found in healthy individuals. The third complementarity determining regions (CDR3) of the T cell receptor (TCR) alpha and beta chains are the putative contact sites for peptide fragments of MBP bound in the groove of the HLA molecule. The TCR V gene usage and CDR3s of these MBP-reactive hprt-T cell clones are homologous to TCRs from other T cells relevant to MS, including T cells causing experimental allergic encephalomyelitis (EAE) and T cells found in brain lesions and in the cerebrospinal fluid (CSF) of MS patients. In vivo activated MBP-reactive T cells in MS patients may be critical in the pathogenesis of MS.

Inhibitory effects of elevated temperature on human cytokine production and natural killer activity.

Febrile reactions often occur in cancer patients given various biological response modifiers such as alpha- or gamma-interferon or interleukin-2. The present studies were undertaken to determine the effects of moderately elevated temperatures (39 degrees C) on various immunological functions related to host defense against malignant cells. The production of the cytokines interleukin-1, interleukin-2, erythroid burst-promoting activity, and granulocyte-macrophage colony-stimulating factor from activated human mononuclear cells was assessed in vitro at 34, 37, and 39 degrees C and found to be reduced at 39 degrees C. The natural killer activity of human mononuclear cells preincubated for 18 h at various temperatures was also significantly reduced (P less than 0.001) at 39 degrees C. Although the addition of recombinant interleukin-1-beta, interleukin-2, and alpha-interferon during the 18-h incubation augmented natural killer activity at all temperatures, the enhancing effects were least apparent at 39 degrees C. Indomethacin increased cytokine-primed natural killer cell activity at all temperatures but did not reverse the inhibitory effects of elevated temperatures. These results suggest that the fever associated with treatment with pyrogenic cytokines may partially offset the direct stimulatory effects of these substances on cellular immune function.

Cell-mediated inhibition of tumor colony formation in agarose by resting and interleukin 2-stimulated human lymphocytes.

Human nonadherent peripheral blood mononuclear cells (PBMC) isolated from nonimmunized donors were preincubated for 18 h in medium alone or medium containing the lymphokine interleukin 2 and subsequently cocultured with tumor cells derived from malignant tumor cell lines or from fresh human tumors. The cell suspensions were subsequently inoculated into agarose; 14 days later, new tumor colony formation was determined. Although the different tumor cells displayed a wide range of sensitivity to the PBMC, in each instance, the number of colonies formed by the tumor cells exposed to the PBMC was consistently reduced relative to that of control cells. The inhibitory effect on the colony-forming cells was especially pronounced with PBMC preincubated with interleukin-2 and was dependent on the ratio of tumor cells to PBMC in the culture. This assay system provides an alternative to the standard 51Cr release assays in assessing the immunomodulatory effects of lymphokines and in quantitating the cytolytic or cytostatic activity of various effector cells against neoplastic stem cells from established cell lines and from heterogeneous cell preparations derived from fresh human tumors.

Phase I evaluation of recombinant interleukin-2 in patients with advanced malignant disease.

Seventeen patients with refractory malignant tumors were treated with recombinant human interleukin-2 (IL-2) administered by weekly bolus intravenous (IV) injection in a phase I dose escalation trial. Patients received 10,000 to 1,000,000 U/m2 per injection over a course of 3 to 33 weeks. Toxicity was dose related and consisted primarily of fever, chills, nausea, and vomiting. Hypotension was observed at doses of 500,000 U/m2 or higher and in one instance was sufficiently severe to require pressors. No tumor regression was seen and all patients eventually developed progressive disease. Blood levels of cortisol, ACTH, prolactin, and growth hormone as well as the acute phase reactant C-reactive protein (CRP) increased after the administration of IL-2 in most patients. Serum IL-2 levels in excess of 250 U/mL were detected five minutes after an IV injection of 1,000,000 U/m2, after which the levels declined with a half-life of approximately 25 minutes. No alteration in lymphocyte surface phenotype or enhancement in natural cell-mediated cytotoxicity against natural killer (NK)-sensitive and resistant tumor cell lines was observed when these parameters were measured weekly just before the IL-2 injections. However, a dramatic but transient decline in circulating lymphocytes and NK activity was noted within hours of receiving IL-2. This effect was independent of fever and was not abrogated by pretreatment with ibuprofen or metyrapone. The majority of patients developed serum IgG antibodies of IL-2 detectable with a sensitive enzyme-linked immunosorbent assay (ELISA) and a nitrocellulose dot blot assay. The development of anti-IL-2 antibodies was not associated with symptoms suggestive of serum sickness, reductions in serum complement levels, or deterioration in lymphocyte tumoricidal activity. This investigation provides insight into the in vivo actions of this potent biological response modifier and will assist in the design of future studies with IL-2 administered alone or in conjunction with other treatment modalities.

IL-7 enhances Ag-specific human T cell response by increasing expression of IL-2R alpha and gamma chains.

Interleukin-7 has demonstrated potent enhancing effects on the growth and differentiation of several immature cell types, including thymocytes, and on survival of resting and antigen activated T cells. In this study, we evaluated the effects of IL-7 on post-thymic antigen-specific T cells from human blood. IL-7 was found to enhance proliferation responses and IFN-gamma secretion of myelin or recall Ag-specific Th1 cells through the selective up-regulation of the IL-2Ralpha and gamma but not beta chains in both an Ag-dependent and Ag-independent manner, but did not affect monocytes, B cells, or NK cells. These functions of IL-7 enhanced the detection of Th1 but not Th2 cell frequency by >2.5 fold, and promoted selection of Ag-specific Th1 cells by the limiting dilution method. Moreover, IL-7 pretreatment conferred increased resistance of CD4+ T cells to CD8+ cell lysis. These studies demonstrate that IL-7 promotes the growth and survival of circulating Ag-specific human Th1 cells through a mechanism that probably involves the gammac common receptor for IL-2 family members that includes IL-7.

Hypoxanthine-guanine phosphoribosyltransferase reporter gene mutation for analysis of in vivo clonal amplification in patients with HTLV type 1-associated Myelopathy/Tropical spastic paraparesis.

We tested a surrogate selection approach utilizing mutation at a reporter gene [hypoxanthine-guanine phosphoribosyltransferase (hprt)] as a probe for in vivo cell division, for detection of clonal T cell expansion in human T lymphotropic (HTLV-1) carriers. Peripheral blood samples from HTLV-1-infected individuals with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) were tested to determine the hprt mutant frequency (Mf). Wild-type and hprt mutant T cell clones were isolated, and clonal identity determined by multiplex PCR and DNA sequencing of T cell receptor (TCR) variable region beta-chain (TCR BV) and third complementarity determining regions (CDR3). Seven samples from HAM/TSP patients were tested, and Mfs were within the normal range for adults (mean 11.3 x 10(-6), max 22.4 x 10(-6), min 5.6 x 10(-6)). The frequency of HTLV-1 infection in wild-type and hprt mutant T cells from HAM/TSP patients was determined to identify enrichment in the mutant fraction of cells. This analysis was performed on 196 isolates from 6 individuals with HAM/TSP. In each case, there is enrichment for virally infected cells in the hprt mutant fraction of isolates. Ten mutant and eight wild-type isolates from sample LS42A (Mf 8.4 x 10(-6)) were tested for clonality by TCR BV PCR and sequencing. Of the 10 hprt mutants, there were two in vivo-expanded clones (four isolates with two identical TCRs, or 80% unique TCR sequences). These studies may provide new insights into the precise mechanism of HTLV-1 leukemogenesis, and aid in the study of mutator phenotypes generated by a combination of Tax-mediated in vivo expansion and mutagenesis.

Unique T-cell receptor junctional sequences found in multiple sclerosis and T-cells mediating experimental allergic encephalomyelitis.

We have used two approaches to isolate TCR sequences that are unique to patients with multiple sclerosis. One strategy was to sequence TCR gene rearrangements directly from MS lesions. The second strategy utilized T-cell clones with a selectable mutation that are found only in MS patients. The selection of T-cell clones with mutations in the hypoxanthine guanine phosphoribosyltransferase (hprt) gene was used to isolate T-cells reactive to myelin basic protein (MBP) in patients with multiple sclerosis (MS). These T-cell clones are activated in vivo, and are not found in healthy individuals. The third complementarity determining regions (CDR3) of the T-cell receptor (TCR) alpha and beta chains are the putative contact sites for peptide fragments of MBP bound in the groove of the HLA molecule. The TCR V gene usage and CDR3s of these MBP-reactive hprt- T-cell clones are homologous to TCRs from other T-cells relevant to MS, including T-cells causing experimental allergic encephalomyelitis (EAE) and T-cells found in brain lesions and in the cerebrospinal fluid (CSF) of MS patients. In vivo activated MBP-reactive T-cells in MS patients may be critical in the pathogenesis of MS.

Expression of granulocyte colony stimulating factor and granulocyte-macrophage colony stimulating factor genes in human astrocytoma cell lines and in glioma specimens.

Expression of granulocyte (G) and granulocyte-macrophage (GM) colony stimulating factor (CSF) genes in human cells of astroglial lineage was studied. Primers for CSFs were used to analyze RNA transcripts in 5 cultured human astrocytoma cell lines and 8 fresh brain specimens by polymerase chain reaction. Constitutive expression of mRNA transcripts of GM-CSF could be detected in all astrocytoma and one neuroblastoma cell lines, and two out of 5 unstimulated astrocytomas, U87MG and U138 MG, expressed G-CSF genes. After stimulation with interleukin (IL)-1 beta + tumor necrosis factor (TNF)-alpha, all cell lines expressed G-CSF. In addition to the cultured cells, we examined gene expression within human malignant astrocytoma, peritumoral brain and autopsied normal brains. The results show that some of the tumor and its surrounding reactive lesions express G- and GM-CSF genes but normal brains do not. The concentration of G- and GM-CSF in supernatants of cultured cells was assessed at the protein level by ELISA. A low level of GM-CSF activity was constitutively present in all astrocytomas. G-CSF was detected in unstimulated U87MG and U138MG and other cell lines could synthesize G-CSF after the stimulation of IL-1 beta and TNF-alpha at the level of mRNA. Furthermore, the concentration of CSFs increased markedly upon stimulation with IL-1 beta and/or TNF-alpha in both a time- and dose-dependent fashion. From these results, it is suspected that astroglial cell-derived CSFs may participate in local immune reactions accompanying infection, degeneration and malignancies in the brain.

Molecular analyses of in vivo hypoxanthine-guanine phosphoribosyltransferase mutations in human T-lymphocytes: II. Demonstration of a clonal amplification of hprt mutant T-lymphocytes in vivo.

Recent molecular analysis of in vivo-derived hprt mutant T-lymphocytes cloned from human blood show that mutants occurring at the normal frequency (approximately 5 X 10(-6) in healthy young individuals generally represent independent hprt mutations. Here we report that in an individual with a high mutant frequency (86-620 X 10(-6],92% (61/66) of the mutant clones are descendents of an original mature T-cell precursor that has undergone in vivo clonal expansion. Therefore, these mutants could represent as few as one original hprt mutation. If so, correcting for the clonal expansion yields a revised calculated mutant frequency (Mf) value for this individual that is near the normal range. These hprt mutant clones all showed identically rearranged T-cell receptor (TCR) beta and gamma gene patterns by Southern blot analysis. All the clones were surface marker CD4+, showed no obvious chromosomal aberration, and had no detectable hprt gene structural alteration. This TCR-defined T-cell clone appears to have expanded in the blood of the individual over a 6-month period and persists at high levels after nearly 4 years. This finding illustrates the need to analyze mutants from individuals with high mutant frequencies at the molecular level in order to estimate hprt mutation frequency from the calculated hprt mutant frequency. The possibility that spontaneous hprt mutants might arise in vivo preferentially in dividing cells, and implications of this, are discussed.

The effect of T-lymphocyte 'clonality' on the calculated hprt mutation frequency occurring in vivo in humans.

The frequency of 6-thioguanine resistant (TGr) mutant T-lymphocytes arising in vivo in humans can be quantified with a cell cloning assay. However, the in vivo proliferation of T-lymphocytes that may include TGr mutant cells can distort the relationship between mutation events and the resulting frequency of mutant cells. The T-cell receptor (TCR) gene rearrangement pattern of T-cell colonies can be used as an independent measure of clonality. Analysis of T-cell 'clonality' in 413 wild type and 1736 TGr mutant isolates from 58 individuals shows that mutant clonality is a frequent occurrence (35/58 individuals = 60.3%). However, a major effect on the mutant frequency corrected for clonality (the calculated 'mutation frequency') was found only in nine samples all of which had mutant frequencies greater than 40 x 10(-6).

Enhanced thromboxane synthesis and vacuolization in human polymorphonuclear leucocytes induced by human lymphokine containing supernatants.

PMN's were cultivated in vitro and treated with supernatants obtained from mitogenic-induced lymphocytes of human tonsil. Cytoplasmic vacuolization increased with time and there was a lower number of neutrophilic clumps in the culture treated with a supernatant containing lymphotoxin. In addition, the PMN's released more thromboxane B2 which was inhibited by indomethacin. We conclude that the action of lymphotoxin on the target PMN's is not mediated by the production of thromboxane B2.

Myelin basic protein peptide specificity and T-cell receptor gene usage of HPRT mutant T-cell clones in patients with multiple sclerosis.

Characterization of T cells responding to autoantigens is central to understanding autoimmune disease. We have used somatic mutation at the hypoxanthine guanine phosphoribosyltransferase (HPRT) gene as an index of T-cell amplification in vivo. With this strategy we previously showed that myelin basic protein-reactive T cells can be isolated only from the HPRT mutant T-cell population cultured from the peripheral blood of multiple sclerosis patients and not from normal individuals. In this study, 165 HPRT mutant and 104 wild-type clones were examined for their reactivity to myelin basic protein and overlapping peptides of myelin basic protein. Five HPRT mutant clones that recognized myelin basic protein and myelin basic protein peptides along with three clones that responded to myelin basic protein peptide alone were isolated. All but one of the eight clones recognized peptides derived from the carboxy terminus of myelin basic protein (p84-168). Sequence analysis showed heterogeneous expression of T-cell receptor V alpha and V beta genes and CDR3s. These studies showed that in vivo amplified autoimmune T cells from patients with long-standing disease use diverse T-cell receptor elements in the recognition of C-terminal myelin basic protein peptides.

Neoplastic and reactive human astrocytes express interleukin-8 gene.

Expression of lymphokine genes in the human astroglial cell lineage was studied. Primers for 9 different human lymphokines, from IL-1 alpha to IL-8, were used to analyze RNA transcripts in 5 cultured human astrocytoma cell lines and fresh brain specimens by PCR. mRNA transcripts for IL-8 were detected in all neuroglial cells. In addition to the cultured cells, we examined IL-8 gene expression within human malignant astrocytoma, peritumoral brain and autopsied normal brains. The result shows that tumor and cells of the surrounding reactive lesion express IL-8 genes, but it is not expressed in normal brains. Next, the concentration of IL-8 in supernatants of cultured cells was measured quantitatively by a solid phase ELISA assay. IL-8 activity was produced constitutively in all astrocytomas and increased markedly upon stimulation with IL-1 beta or TNF alpha, in both a time- and dose-dependent fashion. From these results, it is suspected that astroglial cell-derived IL-8 may take part in neutrophil-mediated inflammation which accompanies infection, degeneration and malignancy in the brain.

Azathioprine associated T-cell mutations in insulin-dependent diabetes mellitus.

Somatic mutations arise regularly in human T lymphocytes. As these events occur at increased frequencies in several autoimmune disorders, presumably because of increased T-cell proliferation, we investigated if this is also true for insulin-dependent diabetes mellitus (IDDM). Mutations of the hypoxanthine guanine phosphoribosyltransferase (hprt) gene measured by 6-thioguanine (TG) selection were studied in 28 patients (60 determinations) enrolled in a prospective double-blinded placebo-controlled study of azathioprine immunosuppression: 17 patients (34 determinations) were receiving azathioprine and 11 (26 determinations) placebo. Mean hprt T-cell mutant frequencies (MFs) were elevated in both patient groups, but only in the azathioprine group were elevations large and statistically correlated with the duration of the therapy. These results suggest that the organ-specific antigenic stimulus of the T-cell proliferation in IDDM does increase mutant cells in the peripheral blood, but this increase is relatively small. However, azathioprine, which is converted to 6-mercaptopurine in vivo, selects and amplifies the hprt mutants that do arise. Clinical azathioprine resistance may be explained by hprt mutations arising in T cells relevant to the underlying autoimmune process. Monitoring for these mutations should allow more effective use of this immunosuppressive agent.

Dissimilarities between purified human interleukin-1 and recombinant human interleukin-2 in the induction of fever, brain prostaglandin, and acute-phase protein synthesis.

The lymphokine interleukin-2 (IL-2) has been shown to enhance natural cell-mediated cytotoxicity, the generation of cytolytic T lymphocytes, and several other aspects of cellular immune function. The gene coding for human IL-2 has been cloned, and recombinant IL-2 will be available for clinical trials in patients with neoplastic, infectious, and immunodeficiency diseases. The present investigation was undertaken to determine if IL-2 was similar to interleukin-1 (IL-1) in its ability to induce fever and the acute-phase response. These studies were based on recent work with recombinant human interferon (IFN)-alpha, which is intrinsically pyrogenic and capable of producing fever by inducing the synthesis of prostaglandin E2 (PGE2). The prospect that IL-2 might exert similar physiologic effects is of critical concern since elevated temperature, PGE2, and acute-phase reactants may profoundly inhibit natural cell-mediated cytotoxicity. Our studies have shown that recombinant human IL-2 is not intrinsically pyrogenic in rabbits at doses as high as 10,000 units/kg when administered by a single intravenous injection. In contrast to IL-1, IL-2 does not stimulate cultured hypothalamus cells to synthesize PGE2, and, furthermore, IL-2 does not elevate serum C-reactive protein levels. These results predict that the administration of IL-2 to patients in doses that stimulate cellular immune function will not induce fever and other toxic side effects frequently seen in individuals receiving IFN.

The development of anti-interleukin-2 antibodies in patients treated with recombinant human interleukin-2 (IL-2).

Approximately 65% (11/17) of cancer patients participating in an ongoing Phase I clinical trial with recombinant interleukin-2 developed nonneutralizing serum IgG anti-interleukin-2 antibodies within 1 month of initiating therapy. These antibodies could be detected using any of several standard techniques including immunoblots and enzyme-linked immunosorbent assays. Western blot analysis and retention experiments with protein A-Sepharose indicate that the antibodies are specific for interleukin-2. The interleukin-2 mutein utilized in this clinical trial (des-ala-ser125 r-IL-2) differs from the major species of the human T cell-derived lymphokine in that it lacks the N-terminal alanine of the native molecule, is not glycosylated, and possesses a serine-cysteine substitution at position 125. Another recombinant interleukin-2, identical to the mutein except that it retains the cysteine at position 125 (des-ala-cys125 r-IL-2), strongly competes with the mutein in competitive enzyme-linked immunosorbent assays, suggesting that the amino acid substitution is not responsible for the recognition of the molecule by serum antibodies. Conversely, nonrecombinant T cell-derived interleukin-2 fails to compete in these assays and is not retained by protein A-Sepharose columns when mixed with high-titer antiserum. These results suggest that the anti-interleukin-2 serum antibodies generated in the course of treatment do not react with the nonrecombinant lymphokine but recognize epitopes peculiar to recombinant forms which are not dependent on the amino acid substitution at position 125. The failure of the antibodies to neutralize the biological activity of recombinant interleukin-2 (IL-2) in lymphocyte proliferation assays and to bind to the native lymphokine suggests that they may not affect IL-2-dependent cellular immune functions in vivo.

Selection of hprt mutant T cells as surrogates for dividing cells reveals a restricted T cell receptor BV repertoire in insulin-dependent diabetes mellitus.

T cells with somatically acquired mutations in the hypoxanthine-guanine phosphoribosyltransferase (hprt) gene were isolated from patients with insulin-dependent diabetes mellitus (IDDM) as representatives of populations potentially enriched for in vivo activated T cells. TCRB gene V region usage among mutant isolates from individual IDDM patients, but not from normal controls, showed a pronounced preference for BV14 and, to a lesser extent, BV6. Wild-type (nonmutant) isolates did not show such preferences. Extensive in vivo clonal expansions of the BV14 expressing mutant T cells from IDDM patients were revealed by sequence identity of TCRB chain junctional regions. These data support restricted TCRB gene usage in T cell populations enriched for in vivo activated clones in patients with IDDM.

Malignant granular lymphoproliferation after Epstein-Barr virus infection: partial immunologic reconstitution with interleukin-2.

This report describes a patient who developed a malignant proliferation of granular lymphocytes following Epstein-Barr virus (EBV) infection. For many months, his illness resembled prolonged infectious mononucleosis with persistent fatigue, fever, leukocytosis, and serologic evidence of recent primary EBV infection. After approximately 1 year, however, he developed progressive granular lymphocytosis and extensive lymphocytic infiltration of the bone marrow and liver. Tests for EBV DNA in pre- and postmortem tissue samples using a sensitive DNA hybridization technique were negative. Southern blot analysis of DNA prepared from blood mononuclear cells demonstrated clonal T-cell antigen receptor gene rearrangement. Despite increased numbers of circulating lymphocytes with the morphology and surface phenotype of normal donor natural killer (NK) cells, the patient's NK activity was consistently depressed in a standard in vitro assay. However, in vitro incubation with interleukin-2 (IL-2), but not with alpha- or gamma-interferon, increased the NK activity of the patient's lymphocytes. Intravenous recombinant IL-2 treatment transiently increased the patient's blood NK activity and was associated with seroconversion to EBV nuclear antigens but failed to affect the progression of his disease. Our findings indicate that clonal granular lymphocytic proliferation may develop after EBV infection and confirm the utility of DNA hybridization analysis in distinguishing monoclonal from benign immunoreactive lymphoproliferation. Furthermore, our results suggest that certain functionally inert neoplastic granular lymphocytes acquire NK activity when exposed to IL-2.