Reflections on Henry G Kunkel as a mentor in clinical investigation

Henry Kunkel spent nearly his entire professional life doing basic and clinical research at Rockefeller University. Many believe that he deserved to be a Nobel Laureate, not for one line of investigation, but for several in entirely distinct areas of medicine. Many of the leaders in immunology research during the last 50 years, especially research on systemic lupus erythematosus, received their research training in Henry Kunkel's laboratory. In this article, I attempt to illustrate his genius as a mentor from recollections of his scientific style and approach when I was a fellow in his laboratory almost 30 years ago. Henry Kunkel's legacy as a mentor continues today through the continuing contributions of his Fellows and their own trainees in immunological research.

Psychological determinants of fibromyalgia and related syndromes

Fibromyalgia and other chronic pain and fatigue syndromes constitute an increasingly greater societal burden that currently is not being approached effectively by traditional Western medicine. Although the hallmarks of fibromyalgia--chronic widespread pain, fatigue, and multiple other somatic symptoms--have neurophysiologic and endocrinologic underpinnings, these biological aspects derive primarily from psychological variables. Female gender, adverse experiences during childhood, psychological vulnerability to stress, and a stressful, often frightening environment and culture are important antecedents of fibromyalgia. To understand fibromyalgia and related syndromes and to provide optimum care requires a biopsychosocial, not a biomedical, viewpoint.

Pain in fibromyalgia

Just as our caveman forebears were frail in the face of predatory animals, we are frail in today's society of childhood neglect or abuse, bumper-to-bumper traffic, frustration at work, and multiple daily hassles. The same neuroendocrine systems and pain regulatory mechanisms that protected early man during acute stress are still encoded in our genome, but may be maladaptive in psychologically and physiologically vulnerable people faced with chronic stress. Many patients with fibromyalgia become vulnerable because of the long-lasting psychological and neurophysiological effects of negative experiences in childhood. Ill-equipped with positive cognitive, emotional, and behavioral skills as adults, they display maladaptive coping strategies, low self-efficacy, and negative mood when confronted with the inevitable stressors of life. Psychological distress ensues, which reduces thresholds for pain perception and tolerance (already relatively low in women) even further. Converging lines of psychological and neurobiological evidence strongly suggest that chronic stress-related blunting of the HPA, sympathetic, and other axes of the stress response together with associated alterations in pain regulatory mechanisms may finally explain the pain and fatigue of fibromyalgia. Vulnerable people who can be classified by the ACR criteria as having fibromyalgia do not have a discrete disease. They are simply the most ill in a continuum of distress, chronic pain, and painful tender points in the general population.

CD45 and Src-related protein tyrosine kinases regulate the T cell response to phorbol esters

Protein kinase C (PKC)-dependent activation of the Ras signal transduction cascade is essential for induction of the IL-2 promoter during stimulation of T lymphocytes via the T cell receptor (TCR). In this study, the effects of PKC-activating phorbol myristate acetate (PMA) on Ras-dependent activation of transcription from the ets/AP-1 Ras-responsive promoter element were examined in human T cells. Pretreatment of Jurkat cells with the Src-family PTK inhibitor herbimycin A resulted in a 50% inhibition of transactivation of the reporter following incubation with PMA. Evidence was also obtained to suggest the participation of the leukocyte-specific protein tyrosine phosphatase CD45, a regulator of Src-like PTKs, in the PMA-induced activation of the Ras/Raf pathway. First, PMA-induced transactivation of ets/AP-1 is diminished 75% in CD45-negative variants, compared with CD45-positive cells. Second, engagement of CD45 by monoclonal antibodies suppresses the PMA response from the reporter construct. Taken together, these data suggest that Src-related proteins mediate PKC-dependent activation of the Ras/Raf pathway and implicate CD45 in the TCR-independent activation of T lymphocytes induced by agents such as PMA.

Anti-lymphocyte autoantibodies in systemic lupus erythematosus

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Autoantibodies that stabilize the molecular interaction of Ku antigen with DNA-dependent protein kinase catalytic subunit

DNA-dependent protein kinase (DNA-PK) consists of a DNA binding subunit (Ku autoantigen), and a catalytic subunit (DNA-PKcs). In the present study, human autoantibodies that recognize novel antigenic determinants of DNA-PK were identified. One type of autoantibody stabilized the interaction of DNA-PKcs with Ku and recognized the DNA-PKcs -Ku complex, but not bio-chemically purified DNA-PKcs. Another type recognized purified DNA-PKcs. Autoantibodies to Ku (p70/p80 heterodimer), 'stabilizing' antibodies, and antibodies to DNA-PKcs comprise a linked autoantibody set, since antibodies recognizing purified DNA-PKcs were strongly associated with stabilizing antibodies, whereas stabilizing antibodies were strongly associated with anti-Ku. This hierarchical pattern of autoantibodies specific for components of DNA-PK (anti-Ku > stabilizing antibodies > anti-DNA-PKcs) may have implications for the pathogenesis of autoimmunity to DNA-PK and other chromatin particles. The data raise the possibility that altered antigen processing and/or stabilization of the DNA-PKcs-Ku complex due to autoantibody binding could play a role in spreading autoimmunity from Ku to the weakly associated antigen DNA-PKcs.

Cell-type specificity of anti-CD45 autoantibodies in systemic lupus erythematosus

OBJECTIVE

To determine the specificity of anti-CD45 autoantibodies in systemic lupus erythematosus (SLE) for native CD45 and for CD45 expressed by T cells and B cells, and at different stages of cellular activation.

METHODS

CD45 purified from different types of lymphocytes was examined by immunoblotting with sera from patients with SLE. Indirect immunofluorescence experiments were performed with purified anti-CD45 autoantibodies.

RESULTS

IgM anti-CD45 autoantibodies in SLE recognize native CD45 expressed on the surface membrane of viable lymphocytes and CD45 purified from activated peripheral T cells and certain T cell lines, but not CD45 purified from B cells or resting peripheral T cells. The presence or absence of reactivity is independent of the individual isoforms expressed.

CONCLUSION

Recognition of CD45 by IgM antilymphocyte autoantibodies in SLE varies with the lineage and state of activation of the lymphocyte target. This pattern of reactivity is consistent with autoantibody specificities involving CD45 glycoforms, rather than CD45 isoforms.

The 8.5-kb PstI allele of the stress protein gene, Hsp70-2: an independent risk factor for systemic lupus erythematosus in African Americans?

SLE is dramatically more prevalent in persons of African descent than in other populations. Several genes in the class III region of the MHC have been considered as potential susceptibility loci for this disorder, but the primary association(s) remains unknown. The stress protein gene, hsp70-2, is of special interest in this regard because it encodes a protein functionally relevant to antigen processing and presentation and has itself been identified as a putative susceptibility locus in organ-specific autoimmune diseases in Caucasians. To clarify the relationship of the hsp70-2 gene to SLE in African Americans, genomic DNA from 46 patients and 42 appropriately matched control subjects was analyzed for an RFLP of the hsp70-2 gene using the probe pH2.3 and the restriction endonuclease PstI, which identifies alleles of 8.5 and 9.0 kb. The 8.5-kb hsp70-2 allele was associated with SLE in this population (X2 = 8.2473, p = 0.0044). This association was not due to linkage disequilibrium with the C4A deletion or with HLA-DR3, as has been reported in Caucasians with IDDM. These data suggest that the 8.5-kb hsp70-2 allele may be an independent susceptibility marker for SLE in African Americans.

"Anticardiolipin" autoantibodies recognize beta 2-glycoprotein I in the absence of phospholipid. Importance of Ag density and bivalent binding

"Anticardiolipin" autoantibodies (aCL) bind to anionic phospholipids only in the presence of beta 2-glycoprotein I (beta 2GPI), a phospholipid-binding plasma protein. The exact role of beta 2GPI in the antigenic specificity of these autoantibodies is unclear, however. Experiments were performed to determine whether aCL recognize beta 2GPI in the absence of phospholipid or neo-Ags formed as a consequence of the beta 2GPI-phospholipid interaction. Although aCL+ IgG fractions did not bind to beta 2GPI alone in ELISAs that used standard polystyrene immunoassay plates, significant specific binding was detected when beta 2GPI was coated on gamma-irradiated ("high binding") polystyrene plates. This difference was associated with the greater density of beta 2GPI immobilized on the gamma-irradiated plates. Fab' fragments of patient IgG demonstrated little or no binding to immobilized beta 2GPI in ELISA, indicating a critical role for Ab bivalency. Inhibition studies of three aCL+ IgG fractions confirmed their specificity for beta 2GPI and demonstrated low affinity binding to fluid-phase beta 2GPI (Kd values of approximately 10(-5) M). aCL binding to beta 2GPI was not a result of phospholipid contamination of the assays, as determined by microphosphate assay and by lipid extraction of IgG and beta 2GPI preparations. In summary, these experiments indicate that IgG aCL are intrinsically low affinity Abs to beta 2GPI. Ab binding to beta 2GPI on a microtiter plate or anionic phospholipid membrane is dependent upon the marked increase in avidity provided by engagement of both Ag binding sites of a given IgG molecule. The data support the hypothesis that phospholipid-bound beta 2GPI is the physiologic target of aCL.

"Anticardiolipin" autoantibodies recognize beta 2-glycoprotein I in the absence of phospholipid. Importance of Ag density and bivalent binding

"Anticardiolipin" autoantibodies (aCL) bind to anionic phospholipids only in the presence of beta 2-glycoprotein I (beta 2GPI), a phospholipid-binding plasma protein. The exact role of beta 2GPI in the antigenic specificity of these autoantibodies is unclear, however. Experiments were performed to determine whether aCL recognize beta 2GPI in the absence of phospholipid or neo-Ags formed as a consequence of the beta 2GPI-phospholipid interaction. Although aCL+ IgG fractions did not bind to beta 2GPI alone in ELISAs that used standard polystyrene immunoassay plates, significant specific binding was detected when beta 2GPI was coated on gamma-irradiated ("high binding") polystyrene plates. This difference was associated with the greater density of beta 2GPI immobilized on the gamma-irradiated plates. Fab' fragments of patient IgG demonstrated little or no binding to immobilized beta 2GPI in ELISA, indicating a critical role for Ab bivalency. Inhibition studies of three aCL+ IgG fractions confirmed their specificity for beta 2GPI and demonstrated low affinity binding to fluid-phase beta 2GPI (Kd values of approximately 10(-5) M). aCL binding to beta 2GPI was not a result of phospholipid contamination of the assays, as determined by microphosphate assay and by lipid extraction of IgG and beta 2GPI preparations. In summary, these experiments indicate that IgG aCL are intrinsically low affinity Abs to beta 2GPI. Ab binding to beta 2GPI on a microtiter plate or anionic phospholipid membrane is dependent upon the marked increase in avidity provided by engagement of both Ag binding sites of a given IgG molecule. The data support the hypothesis that phospholipid-bound beta 2GPI is the physiologic target of aCL.

Autoregulation of Tcr V region epitopes in autoimmune disease

Normal individuals possess low levels of autoantibodies specific for certain peptide defined regions of T-cell receptor (Tcr) variable regions, particularly CDR1 and Fr3. These regions are predicted to be exposed on the surface of the native molecule and, by analogy and comparison with immunoglobulins, correspond to public idiotype determinants. The anti-Tcr idiotype antibodies appear to be ubiquitous and we propose that they play a role in the regulation of T-cell function. To delineate the parameters of expression of these antibodies, we characterized anti-Tcr antibody activity in normal individuals, in those suffering from the autoimmune diseases rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), and in patients with non-autoimmune arthritis (osteoarthritis) as a disease control. There were significant increases in autoantibody levels in the autoimmune patients. There was also variation in isotype and the particular variable regions recognized. IgM autoantibodies directed against a few peptide defined determinants were elevated in RA, whereas SLE patient sera showed high levels of IgG binding to a broad spectrum of Tcr peptides.

IgG autoantibodies to "switch peptide" determinants of TCR alpha/beta in human pregnancy

The fetus is a natural allograft that is protected from immunologic rejection by a complex set of structural and regulatory mechanisms. We determined whether healthy pregnant women differed significantly from healthy non-pregnant controls in their capacity to produce autoantibodies to defined antigenic determinants of the alpha/beta T-cell receptor. Although controls and pregnant women expressed comparable levels of autoantibodies against an intact recombinant T-cell receptor containing the complete V alpha/V beta structures, analysis of comparative reactivity against individual peptide segments of the molecules, indicated enhanced reactivity to regions corresponding to the CDR1 of the alpha chain and to the Fr3 of the variable region of the beta chain. A major difference was noted by increased reactivity of IgG autoantibodies of pregnant women to peptides corresponding to the "switch" region joining the variable and constant domains. This was noted with both the Tcr alpha and beta chains and was directed against highly conserved determinants within these molecules. Antibodies to this region are lacking in the non-pregnant controls. It is possible that autoantibodies directed against conserved regions of the T-cell receptor might function in the suppression of T-cell reactivity of fetal determinants.

Synthetic autoantigens of immunoglobulins and T-cell receptors: their recognition in aging, infection, and autoimmunity

Immunoglobulins and their close relatives, the antigen-specific T-cell receptors, are recognition proteins that express structures which readily serve as self-immunogens. Healthy humans can produce antibodies against variable region-defined recognition structures termed idiotypes, as well as against constant region structures, and the levels of these can increase markedly in autoimmune disease; e.g., rheumatoid factors are autoantibodies directed against a conformational determinant of the gamma heavy chain. More recent analyses employing synthetic peptide technologies and construction of recombinant T-cell receptors document that autoantibodies directed against both variable and constant region markers of the alpha/beta T-cell receptor occur in healthy individuals. Alterations in levels of antibody, usage of IgM or IgG isotypes, and specificity for particular peptide-defined regions vary with natural physiological processes (aging, pregnancy), with artificial allografting, with retroviral infection, and with the inception and progression of autoimmune disease (e.g., rheumatoid arthritis, systemic lupus erythematosus). Two of the major autoimmunogeneic regions of the Tcr alpha/beta are "constitutive" markers inasmuch as all individuals tested produce antibodies against these regions. The most frequently observed autoantibodies are against Tcr V beta CDR1 and Fr3 markers. It is hypothesized that these are normally involved in immunoregulation. Autoantibodies usually are not detected against CDR2 region determinants, or the "private idiotypes" defined by the CDR3 region, or the highly conserved FR4 segment specified by the joining gene segment. However, autoantibodies against the CDR2 of the Tcr alpha chain occur in some SLE patients, and healthy pregnant women produce antibodies against the common peptide determinant expressed by the joining gene and the beginning of the C alpha or C beta domain. Although the precise role of the naturally occurring autoantibodies in immunoregulation remains to be determined, modification of the course of autoimmune diseases in experimental rodent models (experimental allergic encephalomyelitis) has been successfully carried out by immunization with synthetic peptides corresponding to the CDR2 and Fr3/CDR3 segments, and immunization of humans with synthetic V beta CDR2 segments may prove helpful in multiple sclerosis. Moreover, infusion of intravenous immunoglobulins has been successful in the treatment of many autoimmune diseases, including examples where levels of T cells bearing particular V beta gene subsets were elevated. The recent knowledge gained from T-cell receptor structural analysis and antigenic modeling holds promise for determining the roles of particular variable domain structures in antigen recognition MHC-restriction and immunoregulation, and in the development of synthetic and recombinant reagents for modulation of autoimmune and infectious diseases.

Onset of polymyositis with autoantibodies to threonyl-tRNA synthetase during pregnancy

A 24-year-old black woman developed polymyositis with autoantibodies to threonyl-tRNA synthetase in the 2nd trimester of her 3rd pregnancy. This was complicated by fetal loss and the development of severe relapsing myositis resistant to corticosteroid and azathioprine therapy. These features were also common in other cases in the literature. Antisynthetase antibodies had not been reported in myositis occurring during pregnancy and may be of interest regarding the pathogenesis of inflammatory myopathy complicating pregnancy.

Carbohydrate specificity of IgM autoantibodies to CD45 in systemic lupus erythematosus

Patients with SLE develop IgM autoantibodies to different isoforms of CD45, the major surface membrane protein tyrosine phosphatase on lymphocytes and other nucleated hemopoietic cells. Because such autoantibodies could have a potential role in the development of immune dysfunction in this disorder, we performed a series of experiments to characterize their antigenic specificity further. Blots of recombinant E. coli fusion proteins encoded by exons 3-7 of the p220 and p180 isoforms were uniformly non-reactive with SLE IgM, suggesting that anti-CD45 autoantibodies in SLE are directed against conformational and/or carbohydrate epitopes, rather than linear polypeptide epitopes. This issue was examined further using chemically and enzymatically modified CD45 purified from T cells by lectin affinity chromatography as substrates. Treatment of CD45 with 25 mM sodium-m-periodate, sufficient to abrogate binding to various lectins, abolished the reactivity with SLE anti-CD45 autoantibodies. On the other hand, digestion of CD45 with neuraminidase enhanced the binding of anti-CD45 autoantibodies from some of the SLE sera. This result probably reflects decreased steric hindrance or charge repulsion because the binding of mouse monoclonal antibodies directed against linear polypeptide epitopes of CD45 was similarly enhanced. Digestion of CD45 with N-glycosidase F had no effect on autoantibody staining. Taken together, these data suggest that IgM anti-CD45 autoantibodies in SLE recognize non-sialylated carbohydrate determinants in the highly O-glycosylated polymorphic domains of CD45.

Autoantibodies to nucleolin cross-react with histone H1 in systemic lupus erythematosus

IgM autoantibodies to nucleolin and histone H1 are strongly associated in the serum of patients with systemic lupus erythematosus. IgM eluted from immobilized nucleolin specifically stained histone H1 blotted to nitrocellulose; conversely, IgM eluates prepared from immobilized histone H1 stained nucleolin blots. We conclude that the linkage of anti-nucleolin and anti-histone H1 autoantibodies in SLE is due, at least in part, to immunologic cross-reactivity between these two autoantigens, which share certain similar structural features.

Lupus anticoagulant activity of autoimmune antiphospholipid antibodies is dependent upon beta 2-glycoprotein I

It has been reported that antiphospholipid autoantibodies do not recognize phospholipid alone, but rather the plasma protein beta 2-glycoprotein I (beta 2GPI), or a beta 2GPI-phospholipid complex. In vitro beta 2GPI binds to anionic phospholipids and inhibits the prothrombinase activity of procoagulant membranes. In light of the fact that lupus anticoagulants, a type of antiphospholipid antibody, have similar anticoagulant properties, the relationship of beta 2GPI to lupus anticoagulant activity was investigated. IgG from patients with autoimmune diseases or syphilis were tested for anticardiolipin reactivity and lupus anticoagulant activity in the presence and absence of beta 2GPI. As expected, anti-cardiolipin reactivity associated with autoimmune disease was beta 2GPI dependent. In contrast, IgG from a patient with syphilis recognized cardiolipin alone and binding was inhibited by beta 2GPI. Autoimmune antiphospholipid antibodies prolonged the dilute Russell viper venom time of normal plasma, but had no effect on beta 2GPI-depleted plasma. Antiphospholipid antibodies associated with syphilis had no anticoagulant effect. RP-1, an anti-beta 2GPI mAb, had anticoagulant effects similar to those of autoimmune antiphospholipid antibodies. These data demonstrate that antiphospholipid autoantibodies exert lupus anticoagulant activity via an interaction with beta 2GPI. These antibodies and RP-1 appear to amplify the anticoagulant effect of beta 2GPI itself.

Autoantibodies to CD45 in systemic lupus erythematosus

Autoantibodies to surface antigens on lymphocytes and other cells of the immune system may contribute to the development of immunoregulatory and other cellular immune abnormalities in patients with active systemic lupus erythematosus. Of special interest in this respect are autoantibodies to CD45 (leukocyte-common antigen, T200), a plasma membrane protein tyrosine phosphatase implicated in the regulation of lymphocyte functional activity, including cytotoxicity, proliferation, and differentiation.

Autoantibodies to human stress proteins. A survey of various rheumatic and other inflammatory diseases

Unselected sera from patients with various rheumatic, inflammatory bowel, and autoimmune skin diseases (n = 268) were examined against human cell lysate by immunoblotting procedures, to determine the prevalence of autoantibodies to stress proteins (heat-shock proteins) hsp60 (homolog of Escherichia coli groEL and mycobacterial 65K antigens), hsp73, and hsp90. Using standard, sensitive and specific assay conditions, IgG and IgM autoantibodies to these stress proteins were not demonstrable, or were detected infrequently, in sera from control subjects (n = 36) and from patients with rheumatoid arthritis, Sjögren's syndrome, ankylosing spondylitis, Reiter's syndrome, systemic lupus erythematosus, and systemic sclerosis. Autoantibodies to hsp60 were relatively more common (greater than or equal to 20% of sera) in patients with mixed connective tissue disease, polymyositis/dermatomyositis, psoriatic arthritis, inflammatory bowel disease, epidermolysis bullosa acquisita, and bullous pemphigoid. Anti-hsp73 autoantibodies were detected in 20% or more of the sera from patients with Lyme disease and ulcerative colitis. Taken together, these data extend the spectrum of autoimmune and inflammatory diseases in which humoral anti-stress protein autoreactivity develops. However, the paucity of humoral autoreactivity to stress proteins in patients with systemic lupus erythematosus and rheumatoid arthritis argues against a direct role of anti-stress protein autoantibodies in the pathogenesis of these disorders.

The University of North Carolina Arthritis Center

The University of North Carolina Arthritis Center combines the broadly-based research agenda of the Thurston Arthritis Research Center with comprehensive interdisciplinary clinical programs in rheumatology, orthopaedics, and pediatric rheumatology. In keeping with the University's long tradition of service to the people of North Carolina, a primary aim of the Center is to provide the citizens of this state with the best available arthritis care and prevention strategies. The approach here is twofold. New knowledge is created by laboratory investigation of basic disease mechanisms, by clinical studies of new therapies, by social and behavioral research to better understand how patients and their families cope and adjust to chronic arthritis, and by health services research that examines arthritis from a societal perspective. This information, together with advances in rheumatology and related fields from Duke and other institutions, is then applied to optimum clinical and educational services for North Carolina patients and their physicians.

Autoantibodies to nucleolin in systemic lupus erythematosus and other diseases

The 110-kDa intracellular phosphoprotein (110K) described previously by this laboratory as a common IgM autoantigen in SLE and certain other systemic autoimmune disorders and viral infections is identified as nucleolin in the present investigation. Using rabbit antiserum to rat nucleolin as a probe, IgM autoantibody-reactive 110K co-migrated with human lymphocyte nucleolin in one- and two-dimensional immunoblots. Rabbit anti-nucleolin also specifically depleted autoreactive 110K from detergent lysates of human cells. Because nucleolin shares amino acid sequence similarity and/or forms dynamic particles with other prominent autoantigens, the present observation raises the possibility that the nucleolin/anti-nucleolin system may be of special significance for the development of humoral autoreactivity to nuclear Ag.

Autoantibodies to nucleolin in systemic lupus erythematosus and other diseases

The 110-kDa intracellular phosphoprotein (110K) described previously by this laboratory as a common IgM autoantigen in SLE and certain other systemic autoimmune disorders and viral infections is identified as nucleolin in the present investigation. Using rabbit antiserum to rat nucleolin as a probe, IgM autoantibody-reactive 110K co-migrated with human lymphocyte nucleolin in one- and two-dimensional immunoblots. Rabbit anti-nucleolin also specifically depleted autoreactive 110K from detergent lysates of human cells. Because nucleolin shares amino acid sequence similarity and/or forms dynamic particles with other prominent autoantigens, the present observation raises the possibility that the nucleolin/anti-nucleolin system may be of special significance for the development of humoral autoreactivity to nuclear Ag.

Stress proteins, autoimmunity, and autoimmune disease

At birth, the immune system is biased toward recognition of microbial antigens in order to protect the host from infection. Recent data suggest that an important initial line of defense in this regard involves autologous stress proteins, especially conserved peptides of hsp60, which are presented to T cells bearing gamma delta receptors by relatively nonpolymorphic class lb molecules. Natural antibodies may represent a parallel B cell mechanism. Through an evolving process of "physiological" autoreactivity and selection by immunodominant stress proteins common to all prokaryotes, B and T cell repertoires expand during life to meet the continuing challenge of infection. Because stress proteins of bacteria are homologous with stress proteins of the host, there exists in genetically susceptible individuals a constant risk of autoimmune disease due to failure of mechanisms for self-nonself discrimination. That stress proteins actually play a role in autoimmune processes is supported by a growing body of evidence which, collectively, suggests that autoreactivity in chronic inflammatory arthritis involves, at least initially, gamma delta cells which recognize epitopes of the stress protein hsp60. Alternate mechanisms for T cell stimulation by stress proteins undoubtedly also exist, e.g., molecular mimicry of the DR beta third hypervariable region susceptibility locus for rheumatoid arthritis by a DnaJ stress protein epitope in gram-negative bacteria. While there still is confusion with respect to the most relevant stress protein epitopes, a central role for stress proteins in the etiology of arthritis appears likely. Furthermore, insight derived from the work thus far in adjuvant-induced arthritis already is stimulating analyses of related phenomena in autoimmune diseases other than those involving joints. Only limited data are available in the area of humoral autoimmunity to stress proteins. Autoantibodies to a number of stress proteins have been identified in SLE and rheumatoid arthritis, but their pathogenetic significance remains to be established. Nevertheless, the capacity of certain stress proteins to bind to multiple proteins in the nucleus and cytoplasm both physiologically and during stress or injury to cells, suggests that stress proteins may be important elements in the "immunogenic particle" concept of the origin of antinuclear and other autoantibodies. In short, this fascinating group of proteins, so mysterious only a few years ago, has impelled truly extraordinary new lines of investigation into the nature of autoimmunity and autoimmune disease.

Specificity of autoantibodies to histone H1 in SLE: relationship to DNA-binding domains

Autoantibodies in the sera of patients with systemic lupus erythematosus were examined with respect to their specificity for proteolytic fragments of histone H1 that retain, or do not retain, DNA-binding domains. 16 of 31 sera contained IgG and IgM antibodies to histone H1. IgM antibodies to H1 in 8 sera (50%) were directed at 18 kD and 20 kD alpha-chymotrypic H1 fragments that bore binding sites for DNA, as identified by staining immunoblots containing the fragments with ssDNA plus 6/0, a mouse monoclonal antibody against ssDNA, IgM with this type of histone H1 specificity did not react with comparably-sized V8 protease fragments of H1. IgM antibodies to H1 in the other patients were directed against entirely different epitopes which were preserved in V8 protease digests of H1. In serial studies of three patients during different phase of their SLE, the level of antibodies against the 18 kD and 20 kD histone H1 fragments varied in parallel with the level of anti-ssDNA antibodies in one and varied inversely in the other two. The data suggest that a significant proportion of autoantibodies to histone H1 are directed at a limited number of epitopes localized to H1 fragments containing DNA-binding sites.

Constitutive expression of a groEL-related protein on the surface of human gamma/delta cells

Rabbit antibodies to hsp58 (P1), the human homologue of the Escherichia coli stress protein groEL, react specifically in indirect immunofluorescence and complement-dependent microcytoxicity experiments with a cell surface antigen expressed constitutively by T cell lines bearing gamma/delta receptors. This anti-hsp58-reactive antigen is not demonstrable on T cells that express alpha/beta receptors or on various cells that lack T cell receptors. Certain evidence was obtained to suggest that the target antigen on the surface of gamma/delta T cells is a approximately 77-kD protein distinct from intracellular hsp58 and known members of the hsp70 stress protein family. While the exact nature and significance of this anti-hsp58-reactive protein remain to be determined, these data may help to clarify the roles of groEL-related stress proteins and gamma/delta cells that recognize groEL homologous in immunologic defense against infection and in autoimmune disease.

Autoantibodies specific for different isoforms of CD45 in systemic lupus erythematosus

Nearly one-third of IgM antilymphocyte autoantibody-positive sera from patients with systemic lupus erythematosus (SLE) contain IgM antibodies to one or more 180-220-kD molecules (p180, p190, p205, and p220) in blots of glycoproteins purified from T cells by wheat germ agglutinin affinity chromatography. Identity of these IgM targets with multiple isoforms of CD45 was established by their specific depletion from T cell glycoproteins by immunoprecipitation with T191, a monoclonal antibody (mAb) that reacts with an epitope common to all CD45 isoforms. Although the anti-CD45 autoantibodies recognize higher molecular weight isoforms primarily, antigenic specificity in this system is quite heterogeneous and includes multiple distinct CD45 isoforms on different types of T cells that are, at least in part, different from those reactive with mAbs 2H4 and UCHL-1. Because CD45 is a major membrane protein tyrosine phosphatase that plays a critical role in antigen-induced T cell activation, the present data may be relevant to some of the antilymphocyte antibody-mediated immunologic abnormalities that characterize SLE and related autoimmune diseases.

Glycoprotein specificity of cold-reactive IgM antilymphocyte autoantibodies in systemic lupus erythematosus

Sera from patients with systemic lupus erythematosus frequently contain IgM antibodies to glycoproteins of Mr 46,000 and approximately 200,000 isolated from nonionic detergent lysates of mature T cells by affinity chromatography with solid-phase wheat germ agglutinin. Autoantibodies of this specificity correlate strongly with the presence of IgM anti-T cell autoantibodies, as determined by independent indirect immunofluorescence and complement-dependent microcytotoxicity assays, and are specifically absorbed by incubation of patient serum with viable T cells. Collectively, the data suggest that gp46 and, to a lesser extent, gp approximately 200 represent major targets of IgM antilymphocyte autoantibodies in systemic lupus erythematosus.

Clinical rheumatology training of primary care physicians: the resident perspective

Because nonspecialized physicians provide care for the vast majority of patients with rheumatic disorders, we surveyed 327 internal medicine and family medicine residents with respect to the nature of their training in rheumatology. Although most internal medicine residents had access to rheumatologists for training and had taken formal rheumatology rotations, this was often not the case for family medicine residents. Deficiencies evident in both types of programs included limited access to rheumatology electives; insufficient exposure to certain major categories of rheumatic disease, e.g., the spondyloarthropathies and systemic autoimmune disorders; and lack of direct participatory experience in orthopedics, rehabilitation, and psychosocial aspects of rheumatology.

Reactivity of autoantibodies and DNA/anti-DNA complexes with a novel 110-kilodalton phosphoprotein in systemic lupus erythematosus and other diseases

Utilizing nonionic detergent lysates of human lymphoid and non-lymphoid cells as substrate, IgM and/or IgG antibodies to a 110-kDa/isoelectric point 5.4 phosphoprotein (110K) was demonstrated in serum from patients with SLE or certain other systemic autoimmune disorders by immunoblotting and immunoprecipitation. Ig of this specificity was not demonstrable in serum from normal individuals, but, in a limited survey, was detected in serum from patients with acute hepatitis A or infectious mononucleosis. 110K shares a number of properties with nucleolin, i.e., identical Mr and isoelectric point, localization in both the nucleus and the cytosol, increased expression in rapidly dividing cells, and shown to be distinct from already defined autoantigens of similar size, i.e., topoisomerase I, PM-Scl, and RNA polymerase I. Because 110K could bind denatured DNA, as demonstrated by its specific absorption by DNA-cellulose and by its reactivity with monoclonal anti-ssDNA antibody in the presence of denatured DNA, special efforts were made to distinguish reactivity of pre-formed DNA/anti-DNA complexes in SLE serum from that due to specific anti-110K autoantibodies. Although binding to 110K could be mediated by DNA and anti-DNA in some SLE sera, the accumulated evidence supports the existence of a major new autoantibody system in SLE, other autoimmune diseases, and certain virus infections.

Reactivity of autoantibodies and DNA/anti-DNA complexes with a novel 110-kilodalton phosphoprotein in systemic lupus erythematosus and other diseases

Utilizing nonionic detergent lysates of human lymphoid and non-lymphoid cells as substrate, IgM and/or IgG antibodies to a 110-kDa/isoelectric point 5.4 phosphoprotein (110K) was demonstrated in serum from patients with SLE or certain other systemic autoimmune disorders by immunoblotting and immunoprecipitation. Ig of this specificity was not demonstrable in serum from normal individuals, but, in a limited survey, was detected in serum from patients with acute hepatitis A or infectious mononucleosis. 110K shares a number of properties with nucleolin, i.e., identical Mr and isoelectric point, localization in both the nucleus and the cytosol, increased expression in rapidly dividing cells, and shown to be distinct from already defined autoantigens of similar size, i.e., topoisomerase I, PM-Scl, and RNA polymerase I. Because 110K could bind denatured DNA, as demonstrated by its specific absorption by DNA-cellulose and by its reactivity with monoclonal anti-ssDNA antibody in the presence of denatured DNA, special efforts were made to distinguish reactivity of pre-formed DNA/anti-DNA complexes in SLE serum from that due to specific anti-110K autoantibodies. Although binding to 110K could be mediated by DNA and anti-DNA in some SLE sera, the accumulated evidence supports the existence of a major new autoantibody system in SLE, other autoimmune diseases, and certain virus infections.

Stress proteins, arthritis, and autoimmunity

Stress proteins have been highly conserved during evolution not only because of their fundamental importance in the response of the cell to stressful assaults, but also because they have critical roles in cellular activation and cell growth, regulation of protein function, protein transport, and protein assembly. Research focusing on the basic cell biology of stress proteins is intense at present, and will surely continue to be for some time to come. Of particular interest to immunologists and rheumatologists is the convergence of data in several fields that suggest that stress proteins in microorganisms that commonly infect humans may be triggers of humoral and cellular autoimmune responses and consequent overt autoimmune disease expression. Thus, stress proteins of M tuberculosis and other bacteria are close homologs of stress proteins in mammals, and may be involved in the pathogenesis of adjuvant-induced arthritis in rats and, possibly, of RA and reactive arthritis in humans. A great deal of work remains to be done in this area, including (a) generation and propagation of specifically reactive T cell clones, (b) molecular delineation of the immune recognition elements and critical epitopes shared by microbial stress proteins and host proteins, (c) definition of the relative contribution of alpha beta and gamma delta TCRs to T cell reactivity to stress proteins, and (d) clarification of the circumstances that enable persistent T cell autoreactivity to stress proteins. The data at hand are sufficiently compelling, however, to suggest that vaccination against T cells that recognize stress proteins may eventually become part of our therapeutic armamentarium to prevent or cure some forms of arthritis.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibodies to the constitutive 73-kD member of the hsp70 family of heat shock proteins in systemic lupus erythematosus

Serum from patients with systemic lupus erythematosus (SLE) frequently contain IgM and IgG autoantibodies to the constitutively expressed 73-kD/pI 5.5 member of the hsp70 family of heat shock proteins, as determined by one-dimensional (SDS-PAGE) and two-dimensional (IEF/SDS-PAGE) immunoblotting, and by solid-phase SLE Ig immunoprecipitation experiments using hsp70 protein-specific mAbs as probes. Autoantibodies to hsp70 also were detected in a minority of sera from patients with other rheumatic or viral diseases, but not in normal sera. These data may provide additional insight into etiologic and pathophysiologic mechanisms in this and related autoimmune disorders.

Nature of IgG anti-lymphocyte autoantibody-reactive molecules shed from activated T cells in systemic lupus erythematosus

Shedding of cell-surface antigens that react with anti-lymphocyte autoantibodies in systemic lupus erythematosus (SLE) is well-recognized, but the nature of such molecules is unknown. The present investigation demonstrates the rapid shedding of three IgG antibody target molecules of Mr 55,000, 37,000, and approximately 32,000 from the surface of mitogen-activated peripheral T cells during brief incubation at 37 degrees C. Sera lacking IgG anti-lymphocyte antibodies stained none of the three antigens. Absorption of antibody-positive sera with viable HSB-2 cells, a primitive T-cell line lacking HLA antigens and many CD antigens characteristic of mature peripheral T cells, eliminated staining of the shed molecules. These data delineate the number and estimated molecular mass of anti-lymphocyte autoantibody target molecules that are shed from the surface of T cells, and provide further insight into potential mechanisms by which anti-lymphocyte antibodies contribute to the pathogenesis of SLE and related disorders.

Identification of three major target molecules of IgM antilymphocyte autoantibodies in systemic lupus erythematosus

Three cell lymphocyte antigens of m.w. 55,000, 70,000, and 105,000 to 110,000 were identified by Western blotting as targets of IgM autoantibodies in serum from a group of 49 patients with systemic lupus erythematosus. The 55- and 70-kDa antigens were well expressed on unstimulated peripheral T cells, whereas the 105- to 110-kDa target was demonstrable only on mitogen-activated T cells and lymphoblastoid T cell lines. Localization of these molecules to the plasma membrane was established by cytoabsorption experiments in which IgM antibody staining of blotted antigens was specifically absorbed from systemic lupus erythematosus serum during 4 degrees C incubations with intact lymphocytes, and by their detection in purified lymphocyte plasma membranes. While the identity of these target antigens vis a vis known surface determinants was not defined, their expression on peripheral T cells from multiple donors and on cell lines of both undifferentiated (HSB-2) and phenotypically mature (Jurkat; HUT 78) types excluded alloantigens, major histocompatibility complex-encoded determinants, and most T cell differentiation antigens as candidates in this regard. Expression of the IgM autoantibody targets on HSB-2 cells argues against discrete T subset specificities as well. IgM reactivity with the 55-, 70-, and 105- to 110-kDa antigens by blotting was highly correlated with antilymphocyte antibody activity in complement-dependent cytotoxicity assays (Fisher's p less than 0.001), and paralleled flow microfluorimetric and microcytotoxicity quantitation of IgM antibody activity in serial observations of individual patients studied during different phases of disease activity. Taken together, these data suggest that IgM lymphocytotoxic antibodies in systemic lupus erythematosus are directed predominantly against a limited number of non-T cell subset-specific antigens.

Identification of three major target molecules of IgM antilymphocyte autoantibodies in systemic lupus erythematosus

Three cell lymphocyte antigens of m.w. 55,000, 70,000, and 105,000 to 110,000 were identified by Western blotting as targets of IgM autoantibodies in serum from a group of 49 patients with systemic lupus erythematosus. The 55- and 70-kDa antigens were well expressed on unstimulated peripheral T cells, whereas the 105- to 110-kDa target was demonstrable only on mitogen-activated T cells and lymphoblastoid T cell lines. Localization of these molecules to the plasma membrane was established by cytoabsorption experiments in which IgM antibody staining of blotted antigens was specifically absorbed from systemic lupus erythematosus serum during 4 degrees C incubations with intact lymphocytes, and by their detection in purified lymphocyte plasma membranes. While the identity of these target antigens vis a vis known surface determinants was not defined, their expression on peripheral T cells from multiple donors and on cell lines of both undifferentiated (HSB-2) and phenotypically mature (Jurkat; HUT 78) types excluded alloantigens, major histocompatibility complex-encoded determinants, and most T cell differentiation antigens as candidates in this regard. Expression of the IgM autoantibody targets on HSB-2 cells argues against discrete T subset specificities as well. IgM reactivity with the 55-, 70-, and 105- to 110-kDa antigens by blotting was highly correlated with antilymphocyte antibody activity in complement-dependent cytotoxicity assays (Fisher's p less than 0.001), and paralleled flow microfluorimetric and microcytotoxicity quantitation of IgM antibody activity in serial observations of individual patients studied during different phases of disease activity. Taken together, these data suggest that IgM lymphocytotoxic antibodies in systemic lupus erythematosus are directed predominantly against a limited number of non-T cell subset-specific antigens.

IgG anti-lymphocyte antibodies in systemic lupus erythematosus react with surface molecules shared by peripheral T cells and a primitive T cell line

IgG anti-T cell autoantibodies are common in SLE serum, react preferentially with activated lymphocytes, and exert early-phase inhibitory effects on antigen-induced T cell proliferation. Little is known about the target molecules in this system, however, because the low titer and low avidity of the most interesting antibodies limit their utility in conventional immunoprecipitation analyses. Therefore, Western blotting was used to demonstrate binding of IgG in anti-T cell antibody-positive SLE sera to four surface membrane molecules shared by peripheral T cells and HSB-2 cells. Molecules of Mr 90,000 and 55,000 were particularly reactive: each target was stained by IgG anti-lymphocyte antibodies in 11 patient sera (approximately 85%) in the panel. Targets of Mr 37,000 and 105,000 were encountered less frequently (six of 13 and one of 13 patients, respectively). It is unlikely that alloantibodies contributed to the staining patterns observed because reactivity with the four targets was consistently present when cell preparations from multiple unrelated donors were examined. The target molecules were localized to the plasma membrane by whole cell absorption/elution experiments, by the failure of chromatin (DNA/histone) to absorb antibodies to these antigens, and through the use of purified membranes as substrate for Western blotting. With the possible exception of the 105,000 Mr molecule, which is a major target in the IgM anti-T cell antibody system, evidence for the existence of neoantigens as a basis for increased reactivity of SLE IgG with activated T cells was not obtained. The identity of the IgG antibody-reactive molecules with respect to known T cell antigens was not determined, although evidence against the existence of antibodies to Tac (IL 2 receptor) and the transferrin receptor was obtained in monoclonal antibody pre-clearing experiments. Nonetheless, the observation that a limited number of major IgG autoantibody target antigens on activated peripheral T cells are shared by HSB-2 cells, a primitive T cell line expressing few of the differentiation antigens characteristic of mature T cells, should provide a basis for more definitive characterization of antigens in this system in the future.

IgG anti-lymphocyte antibodies in systemic lupus erythematosus react with surface molecules shared by peripheral T cells and a primitive T cell line

IgG anti-T cell autoantibodies are common in SLE serum, react preferentially with activated lymphocytes, and exert early-phase inhibitory effects on antigen-induced T cell proliferation. Little is known about the target molecules in this system, however, because the low titer and low avidity of the most interesting antibodies limit their utility in conventional immunoprecipitation analyses. Therefore, Western blotting was used to demonstrate binding of IgG in anti-T cell antibody-positive SLE sera to four surface membrane molecules shared by peripheral T cells and HSB-2 cells. Molecules of Mr 90,000 and 55,000 were particularly reactive: each target was stained by IgG anti-lymphocyte antibodies in 11 patient sera (approximately 85%) in the panel. Targets of Mr 37,000 and 105,000 were encountered less frequently (six of 13 and one of 13 patients, respectively). It is unlikely that alloantibodies contributed to the staining patterns observed because reactivity with the four targets was consistently present when cell preparations from multiple unrelated donors were examined. The target molecules were localized to the plasma membrane by whole cell absorption/elution experiments, by the failure of chromatin (DNA/histone) to absorb antibodies to these antigens, and through the use of purified membranes as substrate for Western blotting. With the possible exception of the 105,000 Mr molecule, which is a major target in the IgM anti-T cell antibody system, evidence for the existence of neoantigens as a basis for increased reactivity of SLE IgG with activated T cells was not obtained. The identity of the IgG antibody-reactive molecules with respect to known T cell antigens was not determined, although evidence against the existence of antibodies to Tac (IL 2 receptor) and the transferrin receptor was obtained in monoclonal antibody pre-clearing experiments. Nonetheless, the observation that a limited number of major IgG autoantibody target antigens on activated peripheral T cells are shared by HSB-2 cells, a primitive T cell line expressing few of the differentiation antigens characteristic of mature T cells, should provide a basis for more definitive characterization of antigens in this system in the future.

Subset specificity of antilymhocyte antibodies in systemic lupus erythematosus. II. Preferential reactivity with T4 + cells is associated with relative depletion of autologous T4 + cells

Using indirect immunofluorescence and flow cytometry, we determined the proportion and number of T3+, T4+, and T8+ cells in the peripheral blood of patients with systemic lupus erythematosus whose sera were positive for cold-reactive antilymphocyte antibodies versus values in patients whose sera were negative for these antibodies. There was a disproportionate reduction in T4+ peripheral lymphocytes when cold-reactive antilymphocyte antibodies preferentially cytotoxic for this subpopulation were present in autologous serum. The decrease in this subset was responsible for a reduction in the T4:T8 ratio; variation in the number and proportion of T8+ cells was insignificant. A similar, but autoantibody-independent, alteration in the T4+ subpopulation was found in patients who were receiving prednisone therapy. A relationship between T cell population abnormalities and systemic lupus erythematosus disease activity, per se, was not observed.

Modulation of IgM anti-lymphocyte antibody-reactive T cell surface antigens in systemic lupus erythematosus

Cold-reactive lymphocytotoxic autoantibodies are present in the serum of most patients with active systemic lupus erythematosus (SLE) and may be important for the development of the lymphopenia and T cell dysfunction characteristic of this disorder. Neither the mechanisms of autoantibody action in this regard, nor the nature of the relevant T cell membrane target molecules have been defined, however. In the present investigation, preincubation of T cells with SLE serum at 37 degrees C reduced their reactivity with SLE IgM anti-lymphocyte autoantibodies, as demonstrated by indirect immunofluorescence and complement-dependent cytotoxicity. Modulation was restricted to SLE IgM autoantibody-reactive antigen; monoclonal antibody staining of various T cell differentiation and activation antigens remained unchanged. Loss of antigen from the surface membrane was rapid, but transient. A nadir was reached after approximately 120 min of 37 degrees C incubation, followed by essentially complete reexpression of antigen several hours later. Although modulation occurred spontaneously at 37 degrees C in the absence of SLE serum, loss of antigen was enhanced by IgM anti-lymphocyte autoantibodies, despite their low thermal amplitude. Modulation was inhibited by sodium azide, by fixation of cells with paraformaldehyde, and by low incubation temperatures. Colchicine and cytochalasin D had no effect on this process, suggesting that the integrity of the cytoskeleton was not essential. Cycloheximide did not prevent loss of antigen, but inhibited its reexpression. In experiments to determine the fate of modulated antigen, both intracytoplasmic accumulation and shedding from the cell surface were demonstrated. Only shedding was increased by the presence of anti-lymphocyte antibodies, however. These studies delineate modulation of T cell membrane antigen as a new mechanism for anti-lymphocyte autoantibody action in SLE. The occurrence of modulation at physiologic temperatures in vitro suggests that a similar phenomenon of potential relevance to T cell dysfunction may obtain in patients with this disorder.

Modulation of IgM anti-lymphocyte antibody-reactive T cell surface antigens in systemic lupus erythematosus

Cold-reactive lymphocytotoxic autoantibodies are present in the serum of most patients with active systemic lupus erythematosus (SLE) and may be important for the development of the lymphopenia and T cell dysfunction characteristic of this disorder. Neither the mechanisms of autoantibody action in this regard, nor the nature of the relevant T cell membrane target molecules have been defined, however. In the present investigation, preincubation of T cells with SLE serum at 37 degrees C reduced their reactivity with SLE IgM anti-lymphocyte autoantibodies, as demonstrated by indirect immunofluorescence and complement-dependent cytotoxicity. Modulation was restricted to SLE IgM autoantibody-reactive antigen; monoclonal antibody staining of various T cell differentiation and activation antigens remained unchanged. Loss of antigen from the surface membrane was rapid, but transient. A nadir was reached after approximately 120 min of 37 degrees C incubation, followed by essentially complete reexpression of antigen several hours later. Although modulation occurred spontaneously at 37 degrees C in the absence of SLE serum, loss of antigen was enhanced by IgM anti-lymphocyte autoantibodies, despite their low thermal amplitude. Modulation was inhibited by sodium azide, by fixation of cells with paraformaldehyde, and by low incubation temperatures. Colchicine and cytochalasin D had no effect on this process, suggesting that the integrity of the cytoskeleton was not essential. Cycloheximide did not prevent loss of antigen, but inhibited its reexpression. In experiments to determine the fate of modulated antigen, both intracytoplasmic accumulation and shedding from the cell surface were demonstrated. Only shedding was increased by the presence of anti-lymphocyte antibodies, however. These studies delineate modulation of T cell membrane antigen as a new mechanism for anti-lymphocyte autoantibody action in SLE. The occurrence of modulation at physiologic temperatures in vitro suggests that a similar phenomenon of potential relevance to T cell dysfunction may obtain in patients with this disorder.

Anti-lymphocyte antibodies in systemic lupus erythematosus

Patients with systemic lupus erythematosus frequently develop antilymphocyte antibodies as measured by complement-dependent cytotoxicity and immunofluorescence assays. Highest titres of both of the major IgM and IgG classes occur during phases of active disease, and their presence is associated with essentially the entire spectrum of immune system functional abnormalities in this disorder. While the full range of antibody specificities requires further clarification, antibodies to many discrete lymphocyte populations have been described, including B cells, T cells, and T cell subsets. Antibodies to T cell subsets are of special interest because of their relationship with subset depletion in vivo, and their capacity to reproduce, through effects on normal cells in vitro, the same types of immunoregulatory abnormalities characteristic of lymphocytes isolated from patients with SLE. Suppressor/inducer and suppressor/effector T cells appear to be the main targets in this regard. Antibodies specific for activated T lymphocytes exist as well, and this type has the unusual property of interfering with events operant in production of/response to interleukin-2, a critical step controlling the expansion of specifically-reactive T cells and the induction of other lymphokines. In addition to complement-mediated lysis and antibody-dependent cell-mediated cytotoxicity, anti-lymphocyte antibodies have the potential to influence immune system function by several non-cytotoxic mechanisms, including surface antigen modulation and ligand/receptor triggering. Despite the large amount of data which has been accumulated concerning the cell type specificity and functional effects of anti-lymphocyte antibodies in SLE, little is known about the nature of the surface membrane molecules with which they react. Application of cell cloning and molecular biology technology should rectify this deficiency in the near future. Although it is likely that antilymphocyte antibodies are of relevance to immune system pathophysiology in SLE, it remains to be determined whether these interesting antibodies reflect secondary events, or have some more fundamental significance.