Differential expression of rheumatoid factor-associated cross-reactive idiotypes in Iranian seropositive and seronegative patients with rheumatoid arthritis.
High levels of rheumatoid factors (RF) are detectable in serum of the majority of patients with rheumatoid arthritis (RA), but 5-10% of patients remain seronegative (SN). Despite clinical and genetic similarities between these two subsets of RA, it has been proposed that they may be regarded as distinct clinical entities.



In the present study a panel of monoclonal antibodies (mAb) recognizing RF-associated cross-reactive idiotypes (CRI) linked to the VH1 (G8), VH4 (LC1), VK3b (17-109) and a mAb recognizing the VK3 subgroup (C7) of immunoglobulin variable region (IgV) gene products were used to quantitate the level of expression of these gene products in serum and synovial fluid of 35 seropositive (SP) and 8 SN RA patients by capture ELISA.



While the concentration and relative proportion of the IgV are recognized by the mAb G8, 17-109 and C7 were significantly higher in serum and synovial fluid of the SP RA, compared to the SN-RA patients (G8, p = 0.009; 17-109, p = 0.0001; C7, p = 0.001). The CRI recognized by the mAb LC1 was highly represented in serum and synovial fluid of the SN-RA patients. There have been no significant differences in the level of expression of these IgV gene products (other than the product recognized by C7 mAb in SP patients) between serum and synovial fluid of either group of patients.



Our results suggest that the expressed repertoire of Ig VH and VK genes in these two subsets of RA is differentially regulated and may be influenced by selective mechanisms leading to positive or negative selection of certain genes.
Dept. of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.|Dept. of Immunology, School of Medicine, Arak University of Medical Sciences, Arak, Iran.
Ghasem
G
Mosayebi
Bone and Joint Research Unit, William Harvey Institute, London, UK.
Mageed
M
Rizgar
Dept. of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Soheila
S
Gharagozloo
Dept. of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Fazel
F
Shokri
D000328:Adult; D000911:Antibodies, Monoclonal; D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000276:immunology*; D003429:Cross Reactions; D005260:Female; D015870:Gene Expression; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood / Q000378:metabolism; D007130:Immunoglobulin Idiotypes / Q000097:blood / Q000235:genetics; D007075:Immunoglobulin M / Q000097:blood / Q000378:metabolism; D007135:Immunoglobulin Variable Region / Q000235:genetics; D008297:Male; D008875:Middle Aged; D012217:Rheumatoid Factor / Q000097:blood* / Q000276:immunology* / Q000378:metabolism; D013582:Synovial Fluid / Q000276:immunology
D000911:Antibodies, Monoclonal; D007070:Immunoglobulin A; D007130:Immunoglobulin Idiotypes; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region; D012217:Rheumatoid Factor