Immunohistochemical demonstration of Epstein-Barr virus nuclear antigens 1 and 2 in post-transplant lymphoproliferative disorders

Lymphoproliferative disorders developing in transplant patients are immunosuppression-induced, Epstein-Barr virus (EBV)-associated lymphoid lesions that vary in histological appearance. Their overall incidence is about 1 to 5% of transplant cases, depending on the nature of the allograft and the type of the immunosuppression used. Most cases are of B-cell type, and EBV plays a crucial role in immortalising and transforming these lymphoid populations. In this study, we analysed 28 cases of posttransplant lymphoproliferative disorders (PTLD) (17 renal and 11 heart/heart-lung) using two antibodies (1H4-1 and PE2) for the detection of two EBV nuclear antigens, EBNA-1 and EBNA-2, respectively. In addition, EBV latent membrane protein (LMP)-1, B- and T-cell immunostaining was also performed. The streptavidin-biotin complex technique was used on paraffin-embedded, formalin-fixed material. Antigen retrieval was achieved by pressure-cooking pretreatment. Eight of the 17 renal and seven of the 11 heart/heart-lung cases were EBNA-1 or EBNA-2 positive. Only two cases showed EBNA-1 and EBNA-2 discordance. All other cases were positive or negative with both antibodies. All 28 cases were positive for EBV-LMP-1; 27 were of B-cell lineage, and the one remaining case was of null immunophenotype. In conclusion, we demonstrated EBNA-1 and -2 immunostaining in 15 of 28 cases of PTLD. Most of the positive cases showed concordance of EBNA-1 and -2 staining. The failure to stain the remaining cases may be due to true heterogeneity of EBNA expression or to false negativity with the antibodies used lacking sensitivity to detect small amounts of EBNA protein.