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Discusses research into mutant T cell clones from multiple sclerosis (MS) patients, which were tested for reactivity to myelin basic protein, an antigen thought to participate in the induction of MS. Clonal assay method; Response of clones to human myelin basic protein; Wild-type clone results; Isolation of T cell clones.

A prodrome is an early set of signs or symptoms that indicate the onset of a disease before more typical symptoms develop. Prodromal stages are well recognized in some neurological and immune-mediated diseases such as Parkinson disease, schizophrenia, type 1 diabetes mellitus and rheumatoid arthritis. Emerging evidence indicates that a prodromal stage exists in multiple sclerosis (MS), raising the possibility of intervention at this stage to delay or prevent the development of classical MS. However, much remains unclear about the prodromal stage of MS and considerable research is needed to fully characterize the prodrome and develop standardized criteria to reliably identify individuals with prodromal MS who are at high risk of progressing to a diagnosis of MS. In this Roadmap, we draw on work in other diseases to propose a disease framework for MS that incorporates the prodromal stage, and set out key steps and considerations needed in future research to fully characterize the MS prodrome, identify early disease markers and develop standardized criteria that will enable reliable identification of individuals with prodromal MS, thereby facilitating trials of interventions to slow or stop progression beyond the prodrome., (© 2022. Springer Nature Limited.)

Background: Multiple Sclerosis (MS) is a growing global health challenge affecting nearly 3 million people. Progress has been made in the understanding and treatment of MS over the last several decades, but cures remain elusive. The National MS Society is focused on achieving cures for MS., Objectives: Cures for MS will be hastened by having a roadmap that describes knowledge gaps, milestones, and research priorities. In this report, we share the Pathways to Cures Research Roadmap and recommendations for strategies to accelerate the development of MS cures., Methods: The Roadmap was developed through engagement of scientific thought leaders and people affected by MS from North America and the United Kingdom. It also included the perspectives of over 300 people living with MS and was endorsed by many leading MS organizations., Results: The Roadmap consist of three distinct but overlapping cure pathways: (1) stopping the MS disease process, (2) restoring lost function by reversing damage and symptoms, and (3) ending MS through prevention. Better alignment and focus of global resources on high priority research questions are also recommended., Conclusions: We hope the Roadmap will inspire greater collaboration and alignment of global resources that accelerate scientific breakthroughs leading to cures for MS.

There is an unmet need in multiple sclerosis (MS) therapy for treatments to stop progressive disability. The development of treatments may be accelerated if novel biomarkers are developed to overcome the limitations of traditional imaging outcomes revealed in early phase trials. In January 2019, the International Progressive MS Alliance convened a standing expert panel to consider potential tissue fluid biomarkers in MS in general and in progressive MS specifically. The panel focused their attention on neurofilament light chain (NfL) in serum or plasma, examining data from both relapsing and progressive MS. Here, we report the initial conclusions of the panel and its recommendations for further research. Serum NfL (sNfL) is a plausible marker of neurodegeneration that can be measured accurately, sensitively, and reproducibly, but standard procedures for sample processing and analysis should be established. Findings from relapsing and progressive cohorts concur and indicate that sNfL concentrations correlate with imaging and disability measures, predict the future course of the disease, and can predict response to treatment. Importantly, disease activity from active inflammation (i.e., new T2 and gadolinium-enhancing lesions) is a large contributor to sNfL, so teasing apart disease activity from the disease progression that drives insidious disability progression in progressive MS will be challenging. More data are required on the effects of age and comorbidities, as well as the relative contributions of inflammatory activity and other disease processes. The International Progressive MS Alliance is well positioned to advance these initiatives by connecting and supporting relevant stakeholders in progressive MS., (Copyright © 2020 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Imaging probes for early detection of hepatocellular carcinoma (HCC) are highly desired to overcome current diagnostic limitations which lead to poor prognosis. The membrane protein glypican-3 (GPC3) is a potential molecular target for early HCC detection as it is over-expressed in >50% of HCCs, and is associated with early hepatocarcinogenesis. We synthesized the positron emission tomography (PET) probe (89)Zr-DFO-1G12 by bioconjugating and radiolabeling the anti-GPC3 monoclonal antibody (clone 1G12) with (89)Zr, and evaluated its tumor-targeting capacity. In vitro, (89)Zr-DFO-1G12 was specifically taken up into GPC3-positive HCC cells only, but not in the GPC3-negative prostate cancer cell line (PC3). In vivo, (89)Zr-DFO-1G12 specifically accumulated in subcutaneous GPC3-positive HCC xenografts only, but not in PC3 xenografts. Importantly, (89)Zr-DFO-1G12 delineated orthotopic HCC xenografts from surrounding normal liver, with tumor/liver (T/L) ratios of 6.65 ± 1.33 for HepG2, and 4.29 ± 0.52 for Hep3B xenografts. It also delineated orthotopic xenografts derived from three GPC3-positive HCC patient specimens, with T/L ratios of 4.21 ± 0.64, 2.78 ± 0.26, and 2.31 ± 0.38 at 168 h p.i. Thus, (89)Zr-DFO-1G12 is a highly translatable probe for the specific and high contrast imaging of GPC3-positive HCCs, which may aid early detection of HCC to allow timely intervention., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Peripheral T cell lymphomas (PTCLs) are a heterogeneous and poorly understood group of non-Hodgkin lymphomas. Here we combined whole-exome sequencing of 12 tumor-normal DNA pairs, RNA sequencing analysis and targeted deep sequencing to identify new genetic alterations in PTCL transformation. These analyses identified highly recurrent epigenetic factor mutations in TET2, DNMT3A and IDH2 as well as a new highly prevalent RHOA mutation encoding a p.Gly17Val alteration present in 22 of 35 (67%) angioimmunoblastic T cell lymphoma (AITL) samples and in 8 of 44 (18%) PTCL, not otherwise specified (PTCL-NOS) samples. Mechanistically, the RHOA Gly17Val protein interferes with RHOA signaling in biochemical and cellular assays, an effect potentially mediated by the sequestration of activated guanine-exchange factor (GEF) proteins. In addition, we describe new and recurrent, albeit less frequent, genetic defects including mutations in FYN, ATM, B2M and CD58 implicating SRC signaling, impaired DNA damage response and escape from immune surveillance mechanisms in the pathogenesis of PTCL.

Acute lymphoblastic leukemia (ALL) is an aggressive hematological tumor resulting from the malignant transformation of lymphoid progenitors. Despite intensive chemotherapy, 20% of pediatric patients and over 50% of adult patients with ALL do not achieve a complete remission or relapse after intensified chemotherapy, making disease relapse and resistance to therapy the most substantial challenge in the treatment of this disease. Using whole-exome sequencing, we identify mutations in the cytosolic 5'-nucleotidase II gene (NT5C2), which encodes a 5'-nucleotidase enzyme that is responsible for the inactivation of nucleoside-analog chemotherapy drugs, in 20/103 (19%) relapse T cell ALLs and 1/35 (3%) relapse B-precursor ALLs. NT5C2 mutant proteins show increased nucleotidase activity in vitro and conferred resistance to chemotherapy with 6-mercaptopurine and 6-thioguanine when expressed in ALL lymphoblasts. These results support a prominent role for activating mutations in NT5C2 and increased nucleoside-analog metabolism in disease progression and chemotherapy resistance in ALL.

Glypican-3 (GPC3) is a developmentally-regulated oncofetal protein that has been established as a clinically-relevant biomarker for early hepatocellular carcinoma (HCC). It is one of the first transcripts to appear during malignant hepatocyte transformation, and is expressed at the protein level in approximately half of high-grade dysplastic macronodules in cirrhotic liver. Several studies show it is expressed in most (75 to 100%) of HCCs confirmed by histopathology. The protein is anchored to the hepatocyte membrane by a glycosyl-phosphatidylinositol (GPI) anchor and shows consistent membrane immunostaining pattern, making it a viable target for immunotherapeutic approaches. Targeting GPC3 for therapeutic intervention is a promising approach for the clinical management of HCC and selected other tumors that express the marker.

Background: The incidence of melanoma is increasing. Fine-needle aspiration (FNA) is critical in documenting recurrent/metastatic disease in established cases. The potential of metastatic melanoma (MM) to mimic epithelial tumors presents a diagnostic dilemma. In liver FNA, the distinction between hepatocellular carcinoma (HCC) and MM is a frequent challenge. Glypican-3 (GPC3), a heparan sulfate proteoglycan, is a highly sensitive and specific marker for HCC. Serum GPC3 was shown to be expressed in 40% of primary melanomas (PMs), but to the authors' knowledge no tissue studies to date have assessed GPC3 expression in MM. In this study, GPC3 protein expression was investigated in FNAs from MM, and in corresponding histologic sections from the primary tumors., Methods: Sixty archival, direct FNA smears or CytoLyt-fixed samples from 50 patients with MM were retrieved together with formalin-fixed, paraffin-embedded specimens available from 17 corresponding PMs. All cases were stained with anti-GPC3 antibody. FNA and core biopsy specimens from HCCs and benign liver were used as positive and negative controls. GPC3 expression was divided into 2 categories: negative (negative or weak cytoplasmic staining) and positive (moderate or strong cytoplasmic with membranous accentuation)., Results: All FNAs from MM cases were negative (0 of 60) for GPC3. The exact 95% Clopper-Pearson confidence interval was 0.0% to 5.96%. Only 1 case of PM (1 of 17; 5.9%) demonstrated weak focal cytoplasmic staining (regarded as negative)., Conclusions: In the current study, all MM and PM cases in archival FNAs and tissue sections were found to be negative for GPC3. These data suggest that GPC3 is not expressed in melanoma using the 1G12 clone., (Copyright 2009 American Cancer Society)

Background: Glypican-3 (GPC3) is a heparan sulfate proteoglycan which is elevated in the serum of patients with hepatocellular carcinoma (HCC), but not in healthy blood donors, or patients with benign liver disease. GPC3 immunohistochemistry (IHC) is a promising marker of HCC in surgical pathology. This study explores the value of GPC3 expression in liver fine-needle aspirates (FNAs) by immunocytochemistry (ICC), and compares its sensitivity and staining intensity with that of IHC., Methods: Archival cytologic material in hepatic FNAs from 20 patients with HCC, 20 patients with metastatic tumors, and 20 patients with benign lesions, were studied. Correlating surgical specimens and/or cell blocks were available for GPC-3 IHC in 16 patients with HCC. All slides were stained with GPC3-1G12 antibody with appropriate positive and negative controls. Staining intensity was graded as 0, no staining; 1, weak cytoplasmic staining; 2, moderate cytoplasmic staining; 3, strong cytoplasmic staining with membranous accentuation. Grades 0 and 1 were regarded as negative; grades 2 and 3 were considered positive for GPC3., Results: In the HCC group, positive staining was found in 18/20 (90%) samples. In contrast, GPC3 ICC of 20/20 (100%) metastatic tumors and 20/20 (100%) benign cases displayed negative staining, no cases showing moderate or strong expression. The sensitivity and specificity of GPC3 in HCC ICC were 90% and 100% respectively. The surgical sections and cell blocks of HCC demonstrated positive staining less frequently, in 11/16 (68.8%) cases, with 12/16 (75%) correlation with ICC., Conclusions: Results indicated positive staining for GPC3 as defined in 90% of liver FNAs from HCC patients. All metastatic tumors and benign aspirates studied were negative for GPC3. ICC was superior to IHC in 25% of cases. This pilot study supports the diagnostic utility of GPC3 in hepatic FNAs to aid in distinction of HCC from metastatic tumors and benign liver lesions.

HPRT mutations in vivo in human T-lymphocytes are useful probes for mechanistic investigations. Molecular analyses of isolated mutants reveal their underlying mutational changes as well as the T-cell receptor (TCR) gene rearrangements present in the cells in question. The latter provide temporal reference points for other perturbations in the in vivo clones as well as evidence of clonal relationships among mutant isolates. Immunological studies and investigations of genomic instability have benefited from such analyses. A method is presented describing a T-cell lineage analysis in a patient with HTLV-1 infection. Lineage reconstruction of an in vivo proliferating HPRT mutant clone allows timing of the integration event to a postthymic differentiated cell prior to the occurrence of HPRT mutations.

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.

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.

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., (Copyright 1999 Academic Press.)

Vaccination with synthetic TCR peptides from the BV5S2 complementarity-determining region 2 (CDR2) can boost significantly the frequency of circulating CD4+ peptide-specific Th2 cells in multiple sclerosis (MS) patients, with an associated decrease in the frequency of myelin basic protein (MBP)-reactive Th1 cells and possible clinical benefit. To evaluate the immunogenicity of CDR2 vs other regions of the TCR, we vaccinated seven MS patients with overlapping BV5S2 peptides spanning amino acids 1-94. Six patients responded to at least one of three overlapping or substituted CDR2 peptides possessing a core epitope of residues 44-52, and one patient also responded to a CDR1 peptide. Of the CDR2 peptides, the substituted (Y49T)BV5S2-38-58 peptide was the most immunogenic but cross-reacted with the native sequence and had the strongest binding affinity for MS-associated HLA-DR2 alleles, suggesting that position 49 is an MHC rather than a TCR contact residue. Two MS patients who did not respond to BV5S2 peptides were immunized successfully with CDR2 peptides from different BV gene families overexpressed by their MBP-specific T cells. Taken together, these results suggest that a widely active vaccine for MS might well involve a limited set of slightly modified CDR2 peptides from BV genes involved in T cell recognition of MBP.

Following induction of experimental encephalomyelitis with a T-cell clone, L10C1, that is specific for the myelin basic protein epitope p87-99, the inflammatory infiltrate in the central nervous system contains a diverse collection of T cells with heterogeneous receptors. We show here that when clone L10C1 is tolerized in vivo with an analogue of p87-99, established paralysis is reversed, inflammatory infiltrates regress, and the heterogeneous T-cell infiltrate disappears from the brain, with only the T-cell clones that incited disease remaining in the original lesions. We found that antibody raised against interleukin-4 reversed the tolerance induced by the altered peptide ligand. Treatment with this altered peptide ligand selectively silences pathogenic T cells and actively signals for the efflux of other T cells recruited to the site of disease as a result of the production of interleukin-4 and the reduction of tumour-necrosis factor-alpha in the lesion.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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.