We previously reported the predominance of the V gamma 3 gene in synovial fluid mononuclear cells (SFMC) from patients with rheumatoid arthritis (RA); the V gamma 3 gene is rare in normal peripheral blood mononuclear cells (PBMC). Our objective was to sequence the nucleotide composition of the junctional region of gamma chain transcripts expressed in gamma delta T cells from RA SFMC and normal PBMC.
cDNA from RA SFMC and normal PBMC were amplified by polymerase chain reaction, and the nucleotide sequences of amplified clones were determined. We compared the frequencies of V gamma-J gamma rearrangements in inframe (functional) and out of frame (nonfunctional) V gamma transcripts to determine the effect of intrinsic gene rearrangement on the expressed repertoire.
Most V gamma genes, including V gamma 9, both inframe and out of frame, were rearranged to the J1/J2 genes, indicating that the intrinsic rearrangement may be influential in molding the mature functional gamma delta T cell repertoire. V gamma 9 transcripts in RA SFMC predominantly used J1/J2, as opposed to JP in normal PBMC. Most N regions displayed extensive diversity in both RA SFMC and normal PBMC, but some functional V gamma 9 transcripts of RA SFMC from one patient showed an identical junctional sequence, and 2 functional clones from different RA SFMC showed an identical junctional sequence, implying that the V gamma 9-J1/J2 transcripts could be controlled by antigenic selection.
These results demonstrate that the prominent occurrence of the J1/J2 genes in all V gamma genes and the oligoclonality of functional V gamma 9 transcripts, in addition to the predominance of the V gamma 3 gene, are striking features of gamma chain transcripts in RA SFMC: