RESTRICTED USAGE OF T-CELL RECEPTOR V-ALPHA J-ALPHA GENE SEGMENTS WITH DIFFERENT NUCLEOTIDE BUT IDENTICAL AMINO-ACID-SEQUENCES IN HLA-DR3(+) SARCOIDOSIS PATIENTS/

Background: Sarcoidosis is a granulomatous disease characterized by th e accumulation of activated T cells in the lungs. We previously showed that sarcoidosis patients expressing the HLA haplotype DR3(17),DQ2 ha d increased numbers of lung CD4(+) T cells using the T cell receptor ( TCR) variable region (V) or 2.3 gene segment product. Ln the present s tudy, the composition of both the TCR alpha- and beta-chains of the ex panded CD4(+) lung T cells from four DR3(17),DQ2(+) sarcoidosis patien ts was examined. Materials and Methods: TCR alpha-chains were analyzed by cDNA, cloning and nucleotide sequencing. TCR beta-chains were anal yzed for V beta usage by now cytometry using TCR V-specific monoclonal antibodies or by the polymerase chain reaction (PCR) using V beta- an d C beta-specific primers. J beta usage was analyzed by Southern blott ing of PCR products and subsequent hybridization with radiolabeled J b eta-specific probes. Results: Evidence of biased J(alpha) gene segment usage by the alpha-chains of V alpha 2.3(+) CD4(+) lung T cells was f ound in four out of four patients. Both different alpha-chain nucleoti de sequences coding for identical amino acid sequences and a number of identically repeated alpha-chain sequences were identified. Tn contra st, the TCR beta-chains of FAGS-sorted V-alpha 2.3(+) CD4(+) lung T ce lls were found, with one exception, to have a nonrestricted TCR V-beta usage. Conclusions: The finding of V-alpha 2.3(+) CD4(+) lung T cells with identical TCR alpha-chain amino acid sequences but with differen t nucleotide sequences strongly suggests that different T cell clones have been selected to interact with a specific sarcoidosis associated antigen(s). The identification of T cells with restricted TCR usage, w hich may play an important role in the development of sarcoidosis, and the possibility of selectively manipulating these cells should have i mportant implications for the treatment of the disease.