Analyis of a T-cell receptor V,3 segment implicated in susceptibility to rheumatoid arthritis: V 2 germline polymorphism does not encode susceptibility

Objectives-The assessment of allelic polymorphism of the T cell receptor gene segment, TCRBV2S1, in rheumatoid arthritis. Methods-A total of 136 patients with rheumatoid arthritis (RA) (ACR criteria) and 150 controls were TCRBV2S1 genotyped using a nested PCR amplification strategy followed by single-strand conformation polymorphism (SSCP) analysis. Results-The SSCP typing method detected two previously unknown alleles of the TCRBV2S1 gene segment. The TCRBV2S1 allele, genotype and inferred phenotype frequencies were similar in the RA patients and controls. No differences were apparent after the RA patients had been partitioned according to their HLADR genotypes. Conclusions-SSCP analysis is a rapid and efficient method of typing T cell receptor germline polymorphisms. Allelic polymorphism of the T cell receptor variable segment, TCRBV2S1, does not influence susceptibility to RA. (Ann Rheum Dis 1993; 52: 891-894) Institute ofMolecular Medicine, John Radcliffe Hospital, Headington, Oxford, United Kingdom K Pile P Wordsworth J Bell Centre Viggo-Petersen 7510, Paris, France F Liote T Bardin F Cornelis Correspondence to: Dr Wordsworth, Molecular Immunology Group, Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DU, United Kingdom. Accepted for publication 3 September 1993 Rheumatoid arthritis (RA) is strongly associated with a limited range of HLA-DR molecules' that form one component of the trimolecular complex (T cell receptor/peptide/ HLA) which is integral to specific immune 2 responses. Several lines of investigation also suggest that CD4-positive T cells are important in the pathogenesis of RA.3 Furthermore, an increasing body of evidence, both from animal models of autoimmunity,4 5 and human disease,6 suggests that a restricted repertoire ofT cell receptors (TCR) and TCR variable gene segments may be involved in this group of disorders. Recent advances in our understanding of the mechanisms by which the mature TCR repertoire is generated in humans allow insights into how potentially pathogenic T cells may develop in RA. The involvement of a particular range of TCR in the pathogenesis of RA requires some knowledge of how the mature T cell repertoire is generated. First, enormous diversity is generated from different combinatorial associations of V (variable), D (diversity), J (junctional) and C (constant) segments, particularly since random addition of nucleotides also occurs at the splice sites.2 Second, there is considerable germline polymorphism (as yet incompletely characterised) at the TCR loci. Although allelic polymorphism was originally described in only four VP segments, V 1, VI36-7, VP2 and VP6-1, it is now recognised that such variation occurs in the majority of V segments.7-9 Two of these germline polymorphisms have been implicated in susceptibility to juvenile rheumatoid arthritisl' and primary Sjogren's syndrome." In both cases, the association was found in only a subset of patients defined either by clinical criteria or HIA typing. Investigation of TCR usage by activated lymphocytes infiltrating the synovium in RA has yielded conflicting results, some of which may be attributable to the variety of techniques that have been employed.'2 However, one recent study demonstrated increased usage of VP2 1 and VP3 1 segments by synovial T cells in RA using the inverse polymerase chain reaction (PCR), a technique which overcomes some of the technical difficulties inherent in studying the TCR repertoire. 13 The recent description of a triallelic polymorphism for the VP 2 1 segment,7 together with the suggestion of involvement of this segment in RA'3 prompted us to investigate germline variation of this TCR segment. The single-strand conformation polymorphism (SSCP) method was used for genotyping because of its ability to identify new alleles7 '4 which may be crucial to disease association studies where 'novel' alleles that are rare in the normal population may be enhanced in a disease group. Patients and methods