Bronchoalveolar lavage macrophage and lymphocyte phenotypes in lung transplant recipients

Background: Recent publications have demonstrated potentially pathologic ch anges in bronchoalveolar lavage (BAL) from clinically stable lung transplan t recipients (SLTRs), but there are few available data on alveolar macropha ges (AMs). We formulated the hypothesis that changes in BAL AM and lymphocy te phenotypes would be apparent even in SLTRs. Methods: A cross-sectional study using a standardized 3 x 60 ml BAL, invest igating lymphocyte and AM phenotypes in 19 SLTRs, 5 subjects with bronchiol itis obliterans syndrome (BOS) and 18 normal control volunteers. BAL lympho cyte and AM markers were assessed using flow cytometry. Results: We confirmed a significant elevation of neutrophils in all lung tr ansplant recipients with a more marked elevation in the BOS subjects. Flow- cytometric analysis showed increased numbers of natural killer (NK;, CD56/C D16-positive) cells, increased CD11b- and CD11c-positive CD3 lymphocytes, i ncreased CD8-positive lymphocytes and increased HLA-DR expression in CD8 ce lls from the lung transplant recipients, when compared with normals (p < .0 05). In contrast, the expression of a number of AM surface markers, associa ted with a range of host defense functions against bacteria, fungi and viru ses (CD11a, CD11b, CD11c, HLA-DR, CD14), was lower in both SLTRs and those with BOS (p < .05). Conclusions: These novel findings are consistent with complex lymphocyte an d macrophage changes that may result from clinically silent infection, part ially suppressed rejection, or both.