PERIBRONCHIAL LYMPHOCYTE-ACTIVATION IN BLEOMYCIN-INDUCED LUNG INJURY

The role of lymphocytes in bleomycin (Bleo)-induced lung injury remain s obscure. In normal hamsters, peribronchial lymphatic tissue (PBLT) h as been found to contain a large population of T lymphocytes responsiv e to interleukin 2 (IL-2) but not to IL-4. Lung injury induced by a si ngle intratracheal instillation of Bleo in hamsters has been ameliorat ed by cyclosporin A (CyA). In the present study, using this model, PEL T-derived lymphocyte function was explored for 28 days after Bleo inst illation. Increase in PELT lymphocytes occurred at five time points in vestigated, reaching highest values on day +7 (p < 0.0025). Cell proli feration in response to concanavalin A was enhanced, while IL-2 +/- th e mitogen had no effect. In contrast to its inactivity in the normal h amster, in the Bleo-injured animal IL-4 alone induced T cell prolifera tion (p = 0.0077) on day +7. CyA therapy initially suppressed and dela yed recovery of the number of lymphocytes and their activation. The re sults of this study suggest the existence of a vulnerable period in Bl eo-induced lung injury and indicate that lymphocytes participate in th e pathogenesis of the insult to the tissue. The unresponsiveness to IL -2 and the emergence of cellular response to IL-4 indicate immune devi ation in PELT-derived T cells.