Interactions between bronchoalveolar lymphocytes and macrophages in heart-lung transplant recipients.

Bronchoalveolar lavages (BAL) were obtained from heart-lung transplant patients. Following transplantation, the number of lymphocytes and macrophages are considerably increased. BAL lymphocytes frequently exhibit donor specific secondary allogeneic proliferation measured in primed lymphocyte testing (PLT) assays. We report our findings regarding a persistence of donor derived macrophages and lymphocytes in BAL during the posttransplant period. The presence of donor specific macrophages causes a proliferative response of alloreactive BAL lymphocytes from the recipient. This "Bronchoalveolar Macrophage Lymphocyte Reaction," or "BMLR," may represent a unique aspect of in vivo interactions associated with lung allograft responses. Comparative studies showed considerably lower PLT responsiveness of peripheral blood lymphocytes than that of BAL lymphocytes. These studies suggest that functional assays on BAL cells may be useful in monitoring lung transplant rejection and other immunological phenomena that affect pulmonary function of heart-lung transplant patients.