We evaluated the change in the percentage of cells of donor origin in
pleural fluid of 13 consecutive patients who underwent lung transplant
ation. Pleural fluid was sampled 2, 4, and 8 days after lung transplan
tation. DNA, which was extracted from the blood of donors and recipien
ts and from the pleural fluid, was amplified using a polymerase chain
reaction technique. i The reaction products were electrophoresed, and
bands indicating amplified human leukocyte antigen (HLA)-DR alleles we
re quantified by determining the area under the curve (AUC) by a densi
tometric analysis. HLA-DR alleles, which were present only in recipien
t cells (recipient I allele), were analyzed and compared to HLA-DR all
eles that were present only in donor cells (donor allele). A dilution
study was first performed to provide a standard curve relating the per
centage of donor and recipient cells in a mixture to their AUC. The AU
C of the recipient alleles did not change significantly over the first
8 postoperative days. The AUC of the donor alleles was less on postop
erative days 4 and 8 than on day 2 (p<0.05). The donor allele AUC on d
ay 8 was <20% of the shared allele AUC, corresponding to <1% of all ce
lls by the dilution study. We conclude that donor cells are rapidly cl
eared from the pleural space after lung transplantation,with <1% of ce
lls of donor origin by postoperative day 8.