Distinct phenotypes of infiltrating cells during acute and chronic lung rejection in human heart-lung transplants.

To differentiate between acute and chronic lung rejection in an early stage, phenotypes of infiltrating inflammatory cells were analyzed in 34 transbronchial biopsies (TBBs) of 24 patients after heart-lung transplantation. TBBs were taken during during acute lung rejection and chronic lung rejection, as diagnosed by clinical data and histopathological investigation. TBBs without rejection and normal lung tissue specimens served as controls. Distinct phenotypes of inflammatory cells were found in acute and chronic lung rejection. T cells were present both in acute and in chronic rejection, but did not differentiate between them. In contrast, B cells with antibody deposition were mainly present in chronic rejection and not in acute rejection. Activated macrophages were present only in acute rejection and not in chronic rejection. In nonrejecting lung transplants, perivascular infiltrating cells were virtually absent. In the biopsy specimen, vessels had to be available for analysis, because the cell phenotypes were best recognized in perivascular infiltrates. The analysis of specific phenotypes of inflammatory cells by immunohistochemistry supports the diagnosis of acute and chronic lung rejection, in particular in those cases in which TBB provides limited tissue without airways.