[Phenotype profile of blood lymphocytes in bronchiolitis obliterans after lung transplantation]

Bronchiolitis obliterans (BO) remains the major complication in long-term survivors with lung transplants, occurring in up to 30% of them. As a non-invasive follow-up of lung recipients, we studied the phenotype of peripheral blood lymphocyte subsets. Using a flow cytometric analysis, we could define a specific pattern during BO. The most important findings were 1) disappearance of the CD19+ B cell population, despite normal or increased immunoglobulin blood levels; 2) marked decrease of the CD4+/CD8+ ratio; 3) dramatic increase in phenotypic cytotoxic effector T cells CD8+S6F1+ (MHC Class I-restricted allocytotoxicity) and CD3+CD4-CD8- (MHC Class I-non restricted allocytotoxicity); 4) marked increase of the CD4+CD29+ (helper/inducer T cell) to CD4+CD45RA+ (suppressor/inducer T cell) ratio associated with the loss of phenotypic suppressor/inducer CD4+CD45RA+ T cells. Moreover, we have shown that the maintenance triple immunosuppressive regimen that consisted of cyclosporin, prednisolone and azathioprine, did not affect the relative distribution of lymphocyte subsets, except for the CD3+CD4-CD8- cytotoxic subset that was slightly decreased under therapy. Thus, using a selected combination of lymphocyte membrane antigens, sequential prospective testing should be useful in the non-invasive follow-up of lung-transplanted patients to predict and halt the progressive course towards BO.