Objective: To establish the extent of clonal expansion of T cell receptor (TCR) gamma delta + T cells in synovial fluid (SF), and the sharing of the clones between affected knee joints from patients with rheumatoid arthritis (RA).
Methods: We quantified, using the polymerase chain reaction (PCR), the level of expression from each of the 4 V gamma gene families. We resolved PCR products on denaturing polyacrylamide gels to measure the proportion of mRNA transcripts contributed by clonally expanded gamma delta T cells. We subcloned and sequenced 509 cDNA clones derived from 8 SF and one peripheral blood sample from 2 patients with RA and one patient with juvenile onset RA to fully characterize the populations of T cell receptor gamma mRNA sequences.
Results: We found in each patient disproportionate expression of a subpopulation of T cell receptor gamma mRNA transcripts. Some of these transcripts are expressed by T cells found in both joints.
Conclusion: Synovial TCR gamma delta + T cells are oligoclonal and some of these T cell clones are common to SF of both joints. The finding of identical T cell sequences from SF of both affected joints from each patient points to a role for gamma delta + T cells in disease progression.