THE REPERTOIRE OF T-LYMPHOCYTES RECOVERED BY BRONCHOALVEOLAR LAVAGE FROM HEALTHY NONSMOKERS

We reasoned that persistent exposure to a limited set of airborne anti gens could drive the preferential expansion of single T-cell clones in the lower respiratory tract of normal individuals. To explore this is sue, the normal human alpha/beta T-cell receptor repertoire was studie d in lung lymphocytes obtained by bronchoalveolar lavage (BAL) from th e lumen of the lower respiratory tract. BAL T-cells obtained from five healthy volunteers were first analysed using polymerase chain reactio n to amplify all known V alpha and V beta genes of the T-cell receptor . T-cells from peripheral blood were used as an internal control Heter oduplex analysis of the amplified products was then performed to asses s the clonal composition of the repertoire of lung- versus blood-deriv ed T-lymphocytes within each amplified variable gene family. In all su bjects, the T-cell repertoire in the lung was largely as heterogeneous as peripheral blood in terms of clonal composition. This indicated la ck of preferential expansion of single T-cell clones. A few T-cell clo nes were simultaneously expanded in blood and lung in all individuals within a limited number of V beta (mean 2.4; range 2-4) and V alpha (m ean 1.6; range 1-3) genes. We also found that lung T-lymphocytes expre ssed all of the V gene families of the T-cell receptor that were expre ssed by peripheral blood T-cells. Our results indicate that T-cell clo nes in the lower respiratory tract of normal individuals are distribut ed according to a largely polyclonal pattern, which corresponds to tha t found in peripheral blood.