Human rheumatoid factors with restrictive specificity for rabbit immunoglobulin G: auto- and multi-reactivity, diverse VH gene segment usage and preferential usage of V lambda IIIb.

Abstract

SummaryTo determine the molecular and functional properties of human rheumatoid factors (RF), we established stable hybridomas and Epstein-Barr virus-transformed B cell lines from the synovial fluid or peripheral blood of three patients with rheumatoid arthritis and one patient with systemic lupus erythematosus. 17 cell lines were obtained that produced high-titer immunoglobulin M (IgM) RF that reacted exclusively with rabbit but not human IgG or IgG of other mammalian species. Certain anti-rabbit IgG RF also had specificity for other mammalian antigens (Ag), including cytoskeletal proteins and intracellular proteins found in HeLa cells, as well as for Ag present in an extract prepared from the cell wall of group A streptococci. 13 of the 17 RF contained h-type light (L) chains, of which 12 were classified serologically as members of the X-L chain variable region (Vx) subgroup, designated VxlII. The heavy chain V region (VH) and Vx sequences of nine of these IgMX tLF were determined at the cDNA level. Five VH genes in three V. families were used by these antibodies (Ab), including V.I (dp21/1-4b and dpl0 [51pl]/ hv1051), V.3 (dp38/3-15 and dp77/13-21), and V.4 (dp70/4-4b). The deduced V gene-encoded amino acid sequences of the X chains of these IgMX tLF confirmed their serological classification as xlII, and they were further classified as members of the relatively uncommon VxlII subgroup, designated VxlIIb. Based on cDNA analyses, nine were the product of three different VxlIIb germline genes. Two such genes, designated hsiggl1150 and hsiggl1295, were cloned and sequenced from genomic DNA. Unique combinations of these V. and VxlIIb genes could be related to distinctive patterns of reactivity among the IgMX RF. Although the V, and Vx regions of these Abs were expressed primarily as germline-encoded sequences, four of nine multireactive Abs had extensive V region mutation, indicative of an Ag-driven process. The finding that xlIIb L chains are preferentially found among anti-rabbit IgG RF, and that some of these Ab have specificity for other protein, cellular, and bacterial Ag, provides new insight into the pathogenesis of RA and related diseases.

Light Chain Variable (VL) Sequences of Rheumatoid Factors (RF) in Patients with Primary Sjögren's Syndrome (pSS): Moderate Contribution of Somatic Hypermutation

“…This indicates a selective expansion of 3 RF B cells subset in pSS. Fang et al 1994 also found a preferential utilization of V 3b family genes among some RFs with specificity for rabbit IgG obtained from the synovial fluid or peripheral blood of patients with RA [32]. In contrast, only two of our V 3 RFs were reactive with the rabbit IgG [16].…”

VH usage and somatic hypermutation in peripheral blood B cells of patients with rheumatoid arthritis (RA)

“…Several recent studies have shown that V H genes used in natural autoantibodies are those preferentially expressed or utilized during fetal development, and rearrangements of these natural autoantibodies are mostly unmutated [8,17,18,31,32,49]. In contrast, V H gene usage in IgM RF from peripheral blood of RA patients has been shown to be genetically heterogeneous and somatically mutated [21,22]. Further, an elevation of somatic hypermutation has been observed in CDRs of V H and V L in two of three IgG RF [20].…”

“…However, the exact mechanisms involved in the pathologic autoantibody response in RA remain unclear. Studies of antibody structure may help to decipher the aetiology of a potentially pathologic autoantibody response in RA [8][9][10][17][18][19][20][21][22].…”

Immunoglobulin variable-region gene usage in systemic autoimmune diseases

“…These findings suggested that in this patient, emergence of Vcontaining autoantibodies during B cell ontogeny may have been the stimulus for central V receptor editing. In this context, V genes are a critical part of a number of human autoantibodies, including antibodies to dsDNA, to La/SSB and Ro/SSA, to laminin, to phospholipids, to collagen, and to histone 2A and rheumatoid factor (RF) (60,(63)(64)(65)(66)(67)(68)(69)(70)(71)(72)(73)(74).…”