Antigen-induced recruitment of circulating lymphocytes to the lungs and hilar lymph nodes of mice challenged intratracheally with alloantigens.

Little is known about the traffic of lymphocytes within the lung and hilar lymph nodes and even less is known about the alterations in such traffic after immunization of animals via the trachea. To explore these phenomena, we developed an intrapulmonary immune response to alloantigens in mice by depositing semiallogeneic spleen cells into their tracheas. We studied lymphocyte traffic in this model by two assays. In one, we assessed the recruitment of nonspecific 51Cr-labeled resting lymphocytes to the lungs and hilar node and in the other, a dual-antigen, dual-isotope assay, we measured the recruitment of both allospecific and nonspecific labeled blast cells to the lungs and hilar nodes. The results indicated: (1) that circulating T lymphocytes that have recently synthesized DNA (blast cells) are retained in lungs and hilar lymph nodes of challenged mice far more readily than a circulating resting T lymphocytes, and (2) that there is at least some preferential retention of lymphocytes with specific reactivity to the alloantigen used for immunization. Although lymphocyte recruitment to the lungs and hilar nodes was observed during the entire 5-day postchallenge interval, most of the allospecific recruitment occurred during the first 48 hours.