T cell repertoire in asthmatic airways before and after ragweed challenge

T cell repertoire in the blood and bronchoalveolar lavage (BAL) fluids from six atopic asthmatics was tested before and after segmentai ragweed challenge. Analyses of cell numbers, differential, and T cell subsets in BAL fluids showed that ragweed challenge was associated with preferential homing of CD4+ T cells to the lungs. A reverse transcriptase-PCR was used to amplify TCR V gene transcripts from unfractionated, CD4+, and CD8+ T cells. Levels of expression of 22 Va and 25 Vβ gene families in BAL fluids were similar to those of the same V genes in blood. Ragweed challenge did not change the levels of expression of these V gene families. The clonality of T cells was estimated by analyzing the diversity of TCR V(D)-J junctional region lengths associated with each Va and Vβ gene family, using sequencing gel electrophoresis. Most V gene families in blood and BAL fluids were associated with multiple junctional region lengths before and after ragweed challenge, indicating polyclonal expression. However, some V gene families were expressed in an oligoclonal manner in unfractionated, CD4+, and CD8+ T cells in BAL fluids before ragweed challenge, as indicated by a few predominant junctional region lengths. Most of these V genes families became polyclonal after challenge. Some V gene families became oligoclonal or developed a new oligoclonal pattern of junctional region lengths in BAL T cells after ragweed challenge. This occurred in both CD4+ and CD8+ T cells and was confirmed by DNA sequence analysis. These findings show that ragweed challenge is associated with polyclonal influx and oligoclonal activation of both CD4+ and CD8+ T cells in the lungs.