In situ hybridization for Epstein-Barr virus NotI repeats in posttransplant lymphoproliferative disorder.

Epstein-Barr Virus-associated posttransplant lymphoproliferative disorder (PTLD) is a serious complication of solid organ transplantation. In PTLD, B-cell expansions range from reactive hyperplasias to large cell lymphomas and are often associated with active Epstein-Barr virus (EBV) infection. The lymphoproliferations may infiltrate transplant allografts and therefore may need to be distinguished from acute cellular rejection (ACR). A total of 36 tissue specimens from 11 transplant patients (six kidney, two heart, three liver) with PTLD were studied for EBV content by automated in situ hybridization (ISH) on formalin-fixed or Bouin's-fixed, paraffin-embedded tissue using a synthetic 3' terminally biotin-labeled oligonucleotide DNA probe from the EBV NotI tandem repeat region. The NotI repeat is abundantly transcribed during productive EBV infection and may encode an EBV early antigen. EBV serologies from the 11 patients showed seven primary acute infections and one acute reactivation. Two serologic studies indicated infection of indeterminant onset, and serology was not performed on one patient. Histologically, seven patients presented with polymorphous infiltrates in transplant allograft biopsies, three of which progressed to disseminated monomorphous cell populations and death within 3 to 6 wk. Tissues examined by ISH from all 11 patients showed nuclear staining for EBV in the atypical lymphoid infiltrates (34/36 specimens). The nuclear signal ranged from a stippled pattern of positivity to homogeneous nuclear staining and was localized predominantly in follicular center cells and immunoblasts, although some smaller lymphocytes also contained the viral genome. ISHs performed on 31 allograft biopsies with ACR from 24 transplant patients (six kidney, five heart, 13 liver) without clinical evidence of PTLD and with serological evidence of past EBV infection were negative for the virus. Cell lines containing EBV in the productive state (EB3 and P3HR1) were positive with ISH for NotI, while a latently infected cell line (Raji) was negative. These data indicate that ISH with the NotI probe identifies amplified genome in EBV infections and is useful in discriminating the atypical infiltrate of EBV-associated PTLD from that seen in ACR.