Analysis of the T cell receptor Vgamma region gene repertoire in bronchoalveolar lavage (BAL) and peripheral blood of atopic asthmatics and healthy subjects.

We analyzed the T cell receptor (TCR) Vgamma repertoire in BAL and peripheral blood (PBL) of three mild stable atopic asthmatics and two non-asthmatic controls. We used the polymerase chain reaction (PCR) to establish the expression of the four Vgamma families, and to detect oligo or monoclonal expansion of gammadelta+ T cells, we resolved the PCR projects on denaturing and non-denaturing gels to find the extent of junctional diversity arising from differences in the lengths of the V(D)J junctions. We also subcloned and sequenced the PCR products to characterize fully the sequence diversity. BAL T lymphocytes from two asthmatic patients (treated with inhaled steroids) expressed only VgammaII and, in one of them, VgammaIIJgamma usage was restricted to JgammaP and JgammaP1 gene segments, contrasting with the VgammaJgamma repertoire found in his respective PBL. Analyses in denaturing and non-denaturing gels showed that the BAL VgammaIIJgammaP and VgammaIIJgammaP1 PCR products resolved into few bands, suggesting deletions at the juctions due to oligoclonal expansion. BAL T lymphocytes from the third asthmatic (not receiving inhaled steroids) expressed VgammaI, II and III, and the sequences of the in-frame TCR transcripts from this asthmatic and one healthy volunteer who expressed a similar BAL VgammaTCR repertoire showed clonal expansion of T cells expressing all three Vgamma families. Our analyses showed that much of the GammaDeltaT cell population found in BAL fluid of humans derives from clonally expanded T cells.