HLA-DRB1 gene sequences in HLA-DR4 positive and negative patients with rheumatoid arthritis

The B cell repertoire of patients with rheumatoid arthritis. II. Increased frequencies of IgG+ and IgA+ B cells specific for mycobacterial heat-shock protein 60 or human type II collagen in synovial fluid and tissue

OBJECTIVE

A qualitative and quantitative analysis of the functional, antigen-specific B cell receptor repertoire of patients with rheumatoid arthritis (RA) in synovial and peripheral compartments.

METHODS

B cells were activated to grow and differentiate at high efficiency in vitro under limiting-dilution conditions. Isotype and specificity of the secreted Ig were tested by enzyme-linked immunosorbent assay.

RESULTS

In contrast to peripheral B cells, most synovial B cells had already switched to IgG/IgA in vivo. The frequencies of B cells specifically recognizing foreign antigens were decreased within the synovial population, whereas the frequencies of B cells specific for type II collagen, mycobacterial heat-shock protein 60 (hsp60), or IgG Fc fragments were significantly increased, revealing a negative correlation in terms of frequencies.

CONCLUSION

B cells specific for human type II collagen, hsp60, and IgG Fc fragments are produced and/or expanded locally within the affected joints of RA patients. Thus, the specific immune system is definitely involved in the local inflammatory and destructive processes.

Natural ligand motifs of closely related HLA-DR4 molecules predict features of rheumatoid arthritis associated peptides

Rheumatoid arthritis (RA), one of the most common autoimmune disorders, is believed to be mediated via. T lymphocytes and genetic studies have shown that it is strongly associated with HLA-DR4. The DR4 subtypes DR4Dw4, DR4Dw14 and DR4Dw15 represent increased risk factors for RA, whereas DR4Dw10 is not associated with the disorder. Our study determines and compares the natural ligand motifs of these MHC class II molecules and identifies 60 natural ligands. At relative position 4 (P4), only the RA-associated DR4 molecules allow, or even prefer, negatively charged amino acids, but do not allow those which are positively charged (Arg, Lys). In the case of DR4Dw10 the preference for these amino acids is reversed. The results predict features of the putative RA-inducing peptide(s). A remarkable specificity, almost exclusively for negative charges (Asp, Glu), is found at P9 of the DR4Dw15 motif. This specificity can be ascribed to amino acid beta57 of the DR beta chain, and gives an important insight into the beta57-association of another autoimmune disease, insulin-dependent diabetes mellitus type I.

Anti-neutrophil cytoplasm antibodies (ANCA) in rheumatoid arthritis: relationship to HLA-DR phenotypes, rheumatoid factor, anti-nuclear antibodies and disease severity

To investigate a possible relationship between the presence of anti-neutrophil cytoplasm antibodies (ANCA), rheumatoid factors (RF), anti-nuclear antibodies (ANA), disease severity and HLA-DR phenotypes, 46 consecutive ANCA+ and 48 ANCA-, clinically well-documented RA patients were studied for RF, ANA and HLA-DR phenotypes. The 46 ANCA+ patients showed predominantly an atypical perinuclear staining pattern (89%). ANCA positivity was associated with higher RF titres (P < 0.005) and advanced functional Steinbrocker grades III/IV (P < 0.015). ANCA+ patients were also more often positive for ANA than ANCA- patients (P < 0.008). There was no correlation between ANCA positivity and certain HLA-DR phenotypes although the frequency of DR4+ (67% vs 52%) and, in particular, of DR4+ blanks (phenotypically homozygous) was increased in ANCA+ as compared to ANCA- patients (20% vs 8%). DR4-DR1-RA patients were twice as frequent in the ANCA- than in the ANCA+ group (22.9% vs 8.7%). Correspondingly, the DR4+DR1- phenotype was increased among ANCA+ RA patients. Regarding functional Steinbrocker grades, the DR4+ phenotypes were slightly but not significantly increased in grades III and IV whereas ANCA positivity was significantly associated with severe functional Steinbrocker grades III/IV (66% ANCA+ vs 39% ANCA-, P < 0.015). ANCA positivity identified a population of RA patients with a long-standing and severe clinical course of the disease. There was no correlation between ANCA positivity and certain HLA-DR phenotypes.

Characterization of an HLA-DR4-restricted T cell clone recognizing a protein moiety of small nuclear ribonucleoproteins (UsnRNP)

In sera of patients with mixed connective tissue disease (MCTD, Sharp Syndrome) high titres of IgG autoantibodies to U1snRNP-specific proteins are found. The isolated occurrence of these autoantibodies is highly associated with the HLA-DR4 haplotype. snRNP-specific T cells are supposed to be involved in this autoantibody production. To address this question we cultured mononuclear cells from MCTD patients and healthy donors with a highly purified UsnRNP preparation from HeLa cells using bulk or limiting dilution cultures. Secondary responses to snRNP were detected only rarely with T cell lines from two patients and two controls, and turned out to be unstable during further expansion. One T cell line derived from a healthy individual retained its snRNP reactivity upon limiting dilution cloning and could be characterized in detail. The CD4+ T cell clone recognized native snRNP particles presented by monocytes in an HLA-DR4 (B1*0401)-restricted manner. Separation of the protein and RNA moieties of snRNP particles revealed that the T cell clone responded specifically to the protein fraction, but not to RNA and diverse control antigens. Sequencing of the T cell receptor alpha and beta chain cDNAs revealed that the clone used the V alpha 14.2 and V beta 14 elements. Upon antigen-specific and mitogenic stimulation the T cell clone showed a Th1-specific cytokine pattern, and did not provide helper activity for in vitro immunoglobulin production. This study demonstrate the presence of self-reactive snRNP-specific T cells in a healthy donor. The T cell clone may not represent a helper T cell for the formation of U1snRNP-specific autoantibodies.