Human monoclonal antibodies demonstrate polyreactivity for histones and the cytoskeleton.

Systemic lupus erythematosus (SLE) and other autoimmune diseases are characterized by immune responses to intracellular, highly conserved antigens such as DNA and histone. In this study, peripheral blood lymphocytes (PBL) from a patient with histone autoantibodies were used to prepare IgM human-human hybridoma cell lines. Indirect immunofluorescence (IIF) was used to identify monoclonal antibodies that bound to cytoskeletal and other cytoplasmic constituents. These supernatants did not bind double-stranded or single-stranded DNA. However, immunoblotting revealed that 7/20 hybridomas selected for their binding to cytoskeletal components produced antibodies that also bound mammalian and avian histones. When peptide fragments of histone were used in immunoblotting experiments, it was found that the monoclonal antibodies bound to the carboxyl terminus of H1, a region previously shown to bind autoantibodies from sera of patients with SLE and drug-induced lupus (DIL). When the amino acid sequences of histones and cytoskeletal components were compared using the Swiss-Prot protein data bank, it was confirmed that there are eight regions of similarity. While the significance of polyreactive human monoclonal antibodies to cytoskeletal components and histones is not understood at present, it is possible that the human histone antibodies represent polyreactive antibodies that arise through the mechanism of molecular mimicry.     

Influence of biological response modifiers of bacterial origin on disease progression in the MRL-lpr model of systemic lupus erythematosus

Murine models of systemic lupus erythematosus exhibit some, but not all of the characteristics of human disease. Disease progression in the animal models is related to autoantibodies, genetics, and inflammatory processes. In this report the effects of two bacterial biological response modifiers (BRM) on disease progression in the MRL-lpr model were investigated. The two BRM tested were C. parvum and Bacillus-Calmette-Guerin (BCG), both of which are stimulators of the reticuloendothelial system and both of which have been shown by others to influence disease progression in NZB/W mice. Treatment of 10-week-old mice with C. parvum led to transient alterations in hepatosplenomegaly and plasma proteinase regulation, which then returned to control values. Treatment with BCG led to even more transient effects on the mice. Neither BRM appeared to impact on disease-associated alterations in autoantibody titres, hepatosplenomegaly, or elevations in plasma proteinase activity. Likewise, treatment of 17-week-old MRL-lpr mice with C. parvum did not influence disease progression as evidenced by survival, autoantibody production, or hepatosplenomegaly. Therefore, in contrast to the NZB/W strain, treatment of the MRL-lpr strain with these BRM does not appear to impact on disease progression. This difference may be due to the influence of the lpr accelerator gene in this model.     

An analysis of the frequency of Sjogren's syndrome in a population of multiple sclerosis patients

We have studied 42 unselected patients with a clinical diagnosis of multiple sclerosis (MS) for clinical and laboratory features of Sjogren's syndrome (SS). The MS patients in this study had similar demographic/epidemiologic features as those previously reported in the literature. The most striking features of the MS patients suggesting a SS diathesis was the presence of dry eyes (xeropthalmia) in six (14%). Although 2/6 of the symptomatic patients and 6/36 of the asymptomatic patients had abnormal tear production (Schirmer's test) this was accounted for by the concomitant use of anti-cholinergic medication. None of the MS patients had autoantibodies (SS-A/Ro, SS-B/La, rheumatoid factor) thought to be characteristic of SS. We conclude that SS, either in isolation or occurring in combination with MS, is uncommon in an MS outpatient setting.     

Normal anti-Klebsiella lymphocytotoxicity in ankylosing spondylitis

We compared in vitro lymphocytotoxicity (LCT) of peripheral blood lymphocytes (PBL), obtained from patients with ankylosing spondylitis (AS) and normal controls (NC). Assays were performed with antibacterial antisera prepared from AS- and NC-derived Klebsiella and coliforms Escherichia coli. LCT assessed by eosin staining was not significantly different in PBL of 12 AS patients and 28 controls when reacted with 3 Klebsiella and 1 E coli antisera. LCT assessed by 51Cr release was not significantly different for PBL of 20 age- and sex-matched pairs of AS patients and NC when reacted with 3 Klebsiella and 1 E coli antisera. Similarly, LCT-51Cr of PBL of 15 matched AS and NC pairs was not significantly different for anti-K21, a serotype putatively implicated in Klebsiella-HLA-B27 antigenic cross-reactivity. Our results do not support the notion of molecular mimicry between Klebsiella and B27 in the pathogenesis of primary AS.     

Clinical and serologic features of patients with polymyositis or dermatomyositis

The clinical and serologic features of 36 patients with polymyositis (PM) or dermatomyositis (DM) were observed over a 5-year period. The mean age of the patients at the time of diagnosis was 48.5 years, and 61% were female. According to widely accepted diagnostic criteria 50% had PM (group I), 14% DM (group II), 11% PM or DM associated with malignant disease (group III) and 25% PM or DM associated with a connective tissue disorder (group V). None of the patients had childhood PM or DM associated with vasculitis (group IV). All the patients had muscle weakness, and 94% of the patients tested had an elevated serum level of creatine kinase. The average delay from the onset of symptoms to diagnosis was 14 months overall but only 2.3 months for the DM patients. Of the 30 patients whose serum was tested, 73% had antinuclear antibodies, with antibodies to nuclear ribonucleoprotein being most common in group V patients and antibodies directed against the Jo-1 antigen being restricted to patients with PM alone (group I).     

Unique and shared features of Golgi complex autoantigens

Here we summarize recent advances in the characterization of autoimmune antigens associated with the Golgi complex. All Golgi autoantigens identified to date are high molecular weight proteins rich in coiled-coil domains and localized to the cytoplasmic face of the Golgi cisternae. The characteristic features of these Golgi autoantigens are interestingly similar to selected human autoantigens reported in other intracellular compartments such as endosome, centrosome, and centromere. The implication of this class of autoantigens in autoimmunity is discussed.     

Characterization of the human autoimmune response to the major C-terminal epitope of the ribosomal P proteins

Autoantibodies to the ribosomal phospho (-P) proteins P0, P1, and P2, collectively referred to as Rib-P, are specifically found in 10-40% of patients with systemic lupus erythematosus (SLE). These antibodies are believed to be correlated with lupus nephritis, hepatitis, and central nervous system involvement. The major immunoreactive epitope of these ribosomal antigens has been localized to the carboxy terminus, which is a highly conserved domain of all three proteins and contains two phosphorylated serine residues. The phosphorylated amino acids of the P proteins are known not to be critical epitope determinants. Furthermore, epitope-mapping studies have shown that the major epitope is located within the last 11 C-terminal amino acids. Using peptide arrays we identified more precisely this shared epitope as the six C-terminal amino acids GFGLFD and elucidated the molecular recognition events of anti-Rib-P antibodies at the amino acid level. We identified Phe(111) and Phe(114) of Rib-P2 as the key residues for the interaction, with further contributions of Gly-112 and Asp-115. This amino acid stretch is also present in proteins of several pathogenic micro-organisms such as Trypanosoma cruzi, Brugia malayi, Pseudomonas aeruginosa, Candida albicans, several Leishmania species, and Bartonella henselae. Using newly developed ELISA systems with a C-terminal peptide (C22) and the recombinant proteins (P0, P1, and P2) as antigens we found a high specificity of anti-Rib-P antibodies for SLE and demonstrated positive correlations with anti-U1-C, anti-Sm-B/B' and anti-D and anti-dsDNA antibodies. The sensitivity and specificity in the peptide (C22) based assay varied between 12.8%/100% and 23.4%/96.7% for SLE, depending on the assigned cutoff. In contrast to other studies, we found no significant correlation of anti-Rib-P reactivity with central nervous system manifestations or renal involvement in SLE patients. We conclude that the epitope motif GFGLFD in the C-termini of the ribosomal P proteins is the key determinant of anti-Rib-P antibodies, and that the C22 peptide and the recombinant proteins can be used equally well for the detection of anti-Rib-P antibodies. The role of the major Rib-P epitope in the development of anti-ribosomal P antibodies and in the pathogenesis of SLE remains a subject of further investigation.     

Autoantigens of the nuclear pore complex

The nuclear envelope (NE) is one of many intracellular targets of the autoimmune response in patients with autoimmune liver disease, systemic lupus erythematosus, and related conditions. In eukaryotic organisms the NE consists of five interconnected regions: an outer nuclear membrane (ONM) that is continuous with the endoplasmic reticulum, an intermembrane or perinuclear space, an inner nuclear membrane (INM) with a unique set of integral membrane proteins, the underlying nuclear lamina, and the pore domains that are regions where the ONM and INM come together. The pore domains are sites of regulated continuity between the cytoplasm and nucleus that are occupied by supramolecular structures, termed nuclear pore complexes (NPCs). Human autoantibodies identified to date bind to specific components in three of the five NE compartments. Autoantigen targets include the lamins A, B, and C of the nuclear lamina, gp210, p62 complex proteins, Nup153, and Tpr within the NPC, and LBR, MAN1, LAP1, and LAP2 that are integral proteins of the INM. Autoantibodies to these NE targets have been shown to be correlated with various autoimmune diseases such as primary biliary cirrhosis, other autoimmune liver diseases and systemic rheumatic diseases. Now that the proteome of the NE is more clearly defined, other autoantibodies to components in this cell compartment are likely to be defined.Abbreviations NE Nuclear envelope - ONM Outer nuclear membrane - INM Inner nuclear membrane - NPC Nuclear pore complex - IIF Indirect immunofluorescence - SLE Systemic lupus erythematosus - PBC Primary biliary cirrhosis - CFS Chronic fatigue syndrome     

Addendum to the International Consensus Statement on testing and reporting of antineutrophil cytoplasmic antibodies. Quality control guidelines, comments, and recommendations for testing in other autoimmune diseases

Antineutrophil cytoplasmic antibody (ANCA) tests are used to diagnose and monitor inflammatory activity in Wegener granulomatosis, microscopic polyangiitis and its renal-limited variant (pauci-immune crescentic glomerulonephritis), and Churg-Strauss syndrome. The International Consensus Statement on testing and reporting of ANCA states that ANCA are demonstrated most readily in these conditions by using a combination of indirect immunofluorescence (IIF) of normal peripheral blood neutrophils and enzyme-linked immunosorbent assays (ELISAs) that detect ANCA specific for proteinase 3 or myeloperoxidase. The group that produced the International Consensus Statement has developed guidelines for the corresponding quality control activities, examples of comments for various IIF patterns and ELISA results, and recommendations for ANCA testing when inflammatory bowel disease and other nonvasculitic ANCA-associated autoimmune diseases are suspected.