Origin of pleural cells after lung transplantation: from donor or recipient?

We evaluated the change in the percentage of cells of donor origin in pleural fluid of 13 consecutive patients who underwent lung transplantation. Pleural fluid was sampled 2, 4, and 8 days after lung transplantation. DNA, which was extracted from the blood of donors and recipients and from the pleural fluid, was amplified using a polymerase chain reaction technique. The reaction products were electrophoresed, and bands indicating amplified human leukocyte antigen (HLA)-DR alleles were quantified by determining the area under the curve (AUC) by a densitometric analysis. HLA-DR alleles, which were present only in recipient cells (recipient allele), were analyzed and compared to HLA-DR alleles that were present only in donor cells (donor allele). A dilution study was first performed to provide a standard curve relating the percentage of donor and recipient cells in a mixture to their AUC. The AUC of the recipient alleles did not change significantly over the first 8 postoperative days. The AUC of the donor alleles was less on postoperative days 4 and 8 than on day 2 (p<0.05). The donor allele AUC on day 8 was <20% of the shared allele AUC, corresponding to <1% of all cells by the dilution study. We conclude that donor cells are rapidly cleared from the pleural space after lung transplantation, with <1% of cells of donor origin by postoperative day 8.