T-CELL REPERTOIRE IN THE BLOOD AND LUNGS OF ATOPIC ASTHMATICS BEFORE AND AFTER RAGWEED CHALLENGE

T cells play a pivotal role in initiating and orchestrating allergic r esponses in asthma. The goal of this work was to learn whether ragweed challenge in the lungs alters the T-cell repertoire expressed in the blood and lungs of atopic asthmatics. Analyses of cell numbers, differ entials, and T-cell subsets in bronchoalveolar lavage (BAL) fluids sho wed that ragweed challenge was associated with preferential recruitmen t of CD4+ T cells into the lungs. A reverse transcriptase-polymerase c hain reaction (RT-PCR) was used to amplify T-cell receptor (TCR) gene transcripts from unfractionated, CD4(+) and CD8(+) T cells in blood an d BAL fluids. As judged by RT-PCR, the usage of TCR Vol and VP gene fa milies in BAL fluids was similar to that in blood. Ragweed challenge d id not change the levels of expression of these V gene families, The c lonality of T cells was estimated by analyzing the diversity of TCR V- (D)-J junctional region nucleotide lengths associated with each Vol an d VP gene family, using sequencing gel electrophoresis. Most V gene fa milies in blood and BAL fluids were associated with multiple junctiona l region lengths before and after ragweed challenge, indicating polycl onal expression. Some V gene families were expressed in an oligoclonal manner in unfractionated, CD4(+), and CD8(+) T cells in BAL fluids be fore ragweed challenge, as indicated by a few predominant junctional r egion lengths. The majority of these V gene families became polyclonal after challenge, compatible with polyclonal T-cell influx during infl ammation immediately after ragweed challenge, However, some V gene fam ilies became oligoclonal or developed a new oligoclonal pattern of jun ctional region lengths in BAL T cells after ragweed challenge. Surpris ingly, this occurred in both CD4(+) and CD8(+) T cells. In one of thes e instances. DNA sequencing of V beta 21 junctional regions in CD8(+) T cells confirmed a change from polyclonal to oligoclonal expression a fter ragweed challenge. These findings show that ragweed challenge is associated with polyclonal influx and oligoclonal activation of both C D4(+) and CD8(+) T cells in the lungs.