Increased Expression of Proliferating Cell Nuclear Antigen in Rejecting Rat Lung Allografts

The aim of this study was to investigate the expression of proliferating cell nuclear antigen (PCNA) as an index of cell proliferation in the Brown Norway (BN) to Lewis (LEW) rat lung allograft model.Following transplantation of BN left lungs into LEW recipients, counts of PCNA-positive cells in the perivascular cellular infiltrate and bronchus-associated lymphoid tissue (BALT) were compared with the histological grade of rejection. Lungs were excised on postoperative days 3 and 5. LEW-to-LEW donor-recipient transplantation was performed as a control. Routinely processed, paraffinembedded sections were selected and stained with PCNA. The PCNA index (% of nuclei positive for PCNA) in the BALT was significantly higher in allograft (19.1%, p < 0.05) compared with isograft (4.2%) at 3 days following transplantation. Similarly, the PCNA index was also greater in the perivascular cellular infiltrates of rejecting lungs (23.9% at 3 days, 31.6% at 5 days). These findings indicate that the cells stimulated by the rejection reaction could be increase the expression of PCNA, and the increasing severity of rejection was paralleled by an increase in the number of PCNA-positive cells. In conclusion, PCNA may be a useful marker of acute cellular rejection in lung allografts