Alveolar macrophage dysfunction in human bone marrow transplant recipients.

We studied the functional characteristics of alveolar macrophages obtained by segmental pulmonary lavage from allogeneic marrow transplant recipients without evidence of ongoing pulmonary infection. The macrophages were mostly of donor marrow origin as judged by Y body fluorescence and were morphologically normal, except for the intracellular accumulation of various amounts of heterogeneous foreign materials. Macrophage function of patients studied within four months after transplantation was impaired, as measured by chemotaxis, phagocytosis and killing of Candida pseudotropicalis, and killing of bacteria. In two patients studied six and 12 months after transplantation, macrophage functions returned toward normal except for a persistent defect in killing of C. pseudotropicalis. Cytomegalovirus was cultured from the lavaged cells of two patients, but the macrophage dysfunction was independent of the cytomegalovirus isolation. These results show that alveolar macrophage dysfunction occurs in marrow transplant recipients and may be associated with their increased risk for pulmonary infections.