Macrophage and lymphocyte chimerism in bronchoalveolar lavage cells from human lung allograft recipients

Background. Chimerism. is suggested to predict a more favourable prognosis in solid organ transplantation. Material and method. Forty-eight bronchoalv eolar lavages from 10 patients (5 females and 5 males) who had received sex -mismatched donor lungs were monitored for varying periods of time, of up t o 2 years, at regular intervals (median 3.0 (0.5-24) months). To investigat e the chimerism. in macrophages and lymphocytes in bronchoalveolar lavage c ells a cloned 2.12 kilobase large biotinylated Y-chromosome-specific DNA-pr obe was used for in situ hybridization. Results. Donor macrophages disappea red in seven patients within the first 6 months after surgery (median 3.0 ( 1-6) months). But 15% donor macrophages could be detected in one patient 1 year and 10% in 2 patients two years after surgery. Donor lymphocytes disap peared in all patients within 3 months (median 1 (0.5-3) months). There was no correlation between periods or severity of acute rejection and percenta ge of donor macrophages and donor lymphocytes in bronchoalveolar lavage. No ne of the patients developed obliterative bronchiolitis. Conclusion. Macrop hage chimerism. in lung may exist for several years. Whilst our results do not elucidate the role of local macrophage chimerism, they do not currently support the view that chimerism prevents rejection.