LYMPHOCYTES MIGRATE FROM THE BRONCHOALVEOLAR SPACE TO REGIONAL BRONCHIAL LYMPH-NODES

The fate of lymphocytes in the bronchoalveolar tract was studied in no rmal young pigs. Peripheral blood lymphocytes were labeled with (51)ch romium or with fluorescein isothiocyanate (FITC) and instilled into a single segmental bronchus. in the first series of experiments, the rad ioactivity was determined in several different parts of the lungs, ind ividual bronchial lymph nodes and a series of other lymphoid and nonly mphoid organs. About two-thirds of the radioactivity was still in the lung at 1 d. The draining lymph node also contained high amounts of ra dioactivity. To exclude that this was caused by labeled cell debris, a n immunohistologic technique was used to localize the FITC-labeled cel ls. There were clearly labeled lymphocytes in the sinusoids of the dra ining nodes. These lymphocytes were characterized by additional surfac e staining, B, T, T-H, and T-S lymphocytes were seen much less often t han in the inoculum while the null and gamma delta T cells showed a pr eference. The lymphocytes reached the bronchial lymph nodes via lympha tics. Lymphocytes in the bronchoalveolar space are not effete cells to be destroyed but return to the immune system. These data provide new interest in the immunologic role of lymphocytes in the bronchoalveolar tract and their kinetics.