Autoantibody profiling in patients with very early rheumatoid arthritis: a follow-up study.

OBJECTIVE: To investigate time courses of autoantibody profiles in patients with early arthritis. PATIENTS AND METHODS: A total of 200 patients with very early arthritis (<3 months duration), among them 102 patients with a final diagnosis of rheumatoid arthritis (RA) and 98 with other rheumatic diseases, were followed up for several years. First follow-up testing was performed in all patients (mean 5 months from baseline), and 82 patients with RA and 35 patients without RA were available for last follow-up testing (mean 32 months from baseline). IgM-rheumatoid factor (RF) was measured by nephelometry, IgA-RF, IgG-RF and anti-cyclic citrullinated peptide antibodies (ACPA) by ELISA, and anti-RA33 antibodies were determined by immunoblotting. RESULTS: At baseline, IgA-RF was detectable in 29% and IgG-RF in 14% of patients with RA while IgM-RF>50 IU/ml (RF50) was positive in 45% of the patients; specificities were 97%, 99% and 96%, respectively. However, the vast majority of patients positive for IgA-RF or IgG-RF were also positive for RF50 or ACPA. During follow-up, the prevalence of ACPA slightly increased while prevalence of all RF subtypes and anti-RA33 decreased. Remarkably, the number of patients positive for RF50 and/or ACPA remained constant, and these patients had a highly increased risk for developing erosive disease in contrast to patients solely positive for anti-RA33. CONCLUSIONS: Testing for RF subtypes did not provide additional diagnostic information. Patients positive for RF50 and/or ACPA had an unfavourable prognosis, irrespectively of changes in the antibody profile during follow-up, whereas anti-RA33 positivity was inversely associated with erosiveness at baseline and at later time points.

B cell epitopes of the heterogeneous nuclear ribonucleoprotein A2: identification of a new specific antibody marker for active lupus disease.

OBJECTIVES: Autoantibody formation and T cell reactivity against the heterogeneous nuclear ribonucleoprotein A2 (hnRNP-A2) has been observed in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Since no differences in epitope recognition were reported and the usefulness of anti-hnRNP-A2 antibodies as diagnostic markers of SLE is unknown, it was our objective to characterise linear B cell epitopes of hnRNP-A2 and to relate the anti-hnRNP-A2 antibody responses to disease activity and clinical features of SLE. METHODS: Sequential serum samples from 15 patients with SLE and sera from patients with other rheumatic diseases and healthy subjects were investigated by ELISA for autoantibody reactivities against a set of 13 overlapping peptides spanning the RNA-binding region of hnRNP-A2. Antibody reactivity against the complete protein was determined by western immunoblotting and ELISA. SLE disease activity was assessed by European Consensus Lupus Activity Measure scores, by SLE Index scores and the British Isles Lupus Assessment index. RESULTS: Anti-peptide antibody reactivities were found in 60% of SLE sera but in only 5% of control samples, and were mainly directed to four peptides, one of which (p155-175) appeared to be immunodominant. Antibodies to p155-175 were exclusively seen in patients with SLE and correlated with clinical disease activity as well as kidney and skin involvement. No correlations were found for the other anti-peptide antibody responses. CONCLUSION: Peptide p155-175 encompasses a disease-specific immunodominant epitope of hnRNP-A2. Since antibodies to p155-175 correlate with disease activity and nephritis, they may be useful as markers for active SLE.

Characterisation of cellular and humoral autoimmune responses to histone H1 and core histones in human systemic lupus erythaematosus.

OBJECTIVE: To address key aspects of anti-histone autoimmunity in systemic lupus erythaematosus (SLE), we performed a detailed characterisation of cellular and humoral autoreactivity to histone H1 and the four core histones H2A, H2B, H3, H4 in patients with SLE and healthy controls. METHODS: Peripheral blood mononuclear cells of 41 patients with SLE and 28 healthy controls were exposed to individual histones and proliferation was measured by [(3)H]-thymidine incorporation. H1-reactive T cell clones were obtained by limiting dilution. Cytokines and total IgG in culture supernatants was measured by ELISA, and autoantibodies to histones were determined by ELISA and immunoblotting. RESULTS: Proliferative responses to H1 were more frequent and more pronounced in cell cultures from patients with SLE (p<0.002), while among the core histones only the response to H2A was increased in patient cultures (p<0.01). All histones elicited a Th1-like cytokine response in patients and controls (high interferon (IFN)gamma and tumour necrosis factor (TNF)alpha, no interleukin (IL)4) with H1 inducing the highest levels of TNFalpha. However, H1 stimulated production of IgG and anti-histone antibodies only in cell cultures derived from patients with SLE. H1-specific T cell clones from patients and controls showed a CD4+CD28+ phenotype and a Th1 cytokine profile. Anti-histone antibodies were detected in 51% of patients with SLE, were primarily directed to H1, H3 and H4, and predominantly of the IgG2 subtype. CONCLUSIONS: Histone H1 constitutes a major B cell and T cell autoantigen in SLE, triggering a proinflammatory Th1 response and driving autoantibody production. This suggests that histone H1 may be of considerable relevance for the pathogenesis of SLE.

The autoimmune response to chromatin antigens in systemic lupus erythematosus: autoantibodies against histone H1 are a highly specific marker for SLE associated with increased disease activity.

This study investigates specificity, sensitivity and concomitant presence of antibodies against histone H1 (H1), nucleosomes (NUC), chromatin (CHR) and dsDNA in patients with systemic lupus erythematosus (SLE), analyses their association with SLE disease activity and characterizes the immunodominant epitope reactivity of anti-H1 antibodies and its relation to SLE disease activity. In a cross-sectional study 394 sera of patients with various rheumatic diseases and healthy subjects were analysed by ELISA for antibodies against H1, NUC, CHR and dsDNA. In addition, a longitudinal analysis was performed that included 121 sequential serum samples derived from 16 SLE patients to assess the relation of these antibodies as well as antibodies to histone H2B to SLE disease activity. To assess epitope reactivity of anti-H1 antibodies overlapping synthetic peptides covering the entire H1 sequence were used. Anti-H1 antibodies yielded a sensitivity of approximately 45% and a specificity of over 98% for SLE, which was comparable to that found for anti-dsDNA antibodies. Anti-CHR and anti-NUC antibodies were of similar sensitivity but slightly (anti-CHR) or considerably (anti-NUC) less specific for SLE (95 and 85%, respectively). The sequential analysis revealed a strong correlation of anti-H1 antibodies with SLE disease activity that was better than the correlation of anti-dsDNA and anti-NUC antibodies, while only weak correlation was found for anti-CHR and anti-H2B antibodies. The immunodominant epitope for anti-HI was localised between amino acids 204 and 218 (pp204-218) and immune reactivity to this epitope also correlated with disease activity. Anti-H1 is a highly specific marker for SLE with a diagnostic value comparable to anti-dsDNA. A positive testing for anti-H1 indicates increased disease activity, as does the appearance of antibodies to its immunodominant epitope pp204-218.

Induction of anti-RA33 hnRNP autoantibodies and transient spread to U1-A snRNP complex of spliceosome by idiotypic manipulation with anti-RA33 antibody preparation in mice.

OBJECTIVE: Anti-RA33 antibodies occur in patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and mixed connective tissue disease (MCTD) and target the A2/B1 protein of the heterogeneous nuclear ribonucleoprotein (hnRNP) complex 4 which forms part of the spliceosome. The aim of the present study was to evaluate the immune response and pathological features induced in mice immunized with anti-RA33 antibodies or patient-derived recombinant single-chain variable fragments (scFv) of anti-RA33 antibodies. METHODS: In the first set of the experiment, two strains of mice (C57BL/6J and BALB/c) were immunized with IgG preparations obtained from two patients with RA and one normal donor. One of the patients had high titer anti-RA33 antibodies; the other one showed weak borderline reactivity. In the second set of the experiment three groups of C57BL/6J mice were immunized, respectively, with affinity-purified (AP) anti-RA33 antibodies, scFv of anti-RA33 antibodies and normal human IgG. The immunological response induced in immunized mice was studied by immunoblotting and line immunoassay (LIA). The presence of arthritis, serositis or myositis was assessed six-months following initial immunization. RESULTS: While anti-RA33 antibodies developed in only two of the mice immunized with different human IgG fractions, anti-RA33 antibodies were clearly detected in 7 sera of 13 mice immunized with AP anti-RA33 antibodies three months after the boost immunization and, moreover, also in 2 sera of 13 mice immunized with scFv of anti-RA33 antibodies. In contrast, mice immunized with normal human IgG did not develop anti-RA33 antibodies. Interestingly, transient autoantibody production against another nuclear autoantigen, U1 snRNP, was observed in 3 C57BL/6J mice immunized with scFv and in 1 mouse immunized with AP autoantibodies. However, these immunological responses were not associated with pathological findings. CONCLUSIONS: Active immunization of naive mice with AP anti-RA33 antibodies and scFv of anti-RA33 antibodies resulted on the one hand in the production of murine anti-RA33 antibodies and led, on the other hand, to transient "autoantibody spread" to snRNP component of the spliceosome and other nuclear autoantigens. This "autoantibody spread" probably reflected disregulation of the idiotypic anti-idiotypic cascade.

Activated T cells in addition to LAV/HTLV-III infection: a necessary precondition for development of AIDS.

Urinary neopterin levels are raised with a high incidence in all risk groups for AIDS. Neopterin elevations reflect activated cellular immunity in risk group members, in some cases independently of LAV/HTLV-III infection. Moreover, we are able to show that in patients receiving multiple blood transfusions at least a transient challenge of cell-mediated immunity occurs, which is indicated in part by increasing neopterin levels. We conclude that neopterin levels are a reliable index for assessment of susceptibility for AIDS when infection with LAV/HTLV-III occurs. Activated status of cell-mediated immunity might predispose infected persons to an overwhelming infection and secondary spreading of LAV/HTLV-III, thus leading to the development of full-blown AIDS or ARC. As a consequence of these observations, T-cell-stimulatory actions and agents should intentionally be avoided. Treatment of AIDS patients with immunosuppressants should be examined. The success of therapeutic regimens should be monitored by measurement of neopterin levels.