Absence of LMP-1 expression in lymphocryptovirus-associated PTLD in 8 macaca fascicularis post-neuronal xenotranplantation

Posttransplant lymphoproliferative disorders (PTLD) are a heterogeneous group of lymphoproliferative diseases that arise due to immunosuppressive drug regimens used with transplantation. Epstein Barr Virus (EBV)-related PTLD represent the large majority of these disorders. The aim of this work is to characterize the PTLD observed in 8 adult immunosuppressed cynomolgus macaques (Macaca fascicularis) (2 males, 6 females, mean age 7 years), which received neural precursors from CTLA4Ig transgenic pigs to treat a pharmacologically-induced form of Parkinson disease. The mean time of occurrence of the first clinical signs of PTLD was 177,62 days (range 110-278) and the mean survival time was 199,87 days (range 117-330 days). Seven of the 8 cases (87.5%) of PTLD occurred in extranodal sites either in the nasal cavity (4/8, 50%), intestinal tract (4/8, 50%), or both (1/8, 12.5%). Cytological and fluorimetric evaluation of the cells revealed the presence of a Bcell lymphoma, medium-size, and high grade. The histological diagnosis and immunohistochemical profile (panel: anti-CD3, anti-CD5, anti-CD20, anti-CD79cyt) is compatible with that of monomorphic PTLD, most frequently diffuse large B-cell lymphoma, high grade. All tumors had a high proliferation index based on a high percentage of Ki-67 (MIB-1) positive cells. Double-labeled immunohistochemistry for Epstein-Barr virus nuclear antigen (EBNA)-2 and B lymphocyte marker CD20 revealed a high percentage of CD20+ neoplastic cells also positive for EBNA-2 (fig. 1), while CD3+ cells in the tumors were negative for EBNA2. RT-PCR and sequencing of transcripts EBNA-1 and Latent Membrane Protein-1 (LMP-1) have been performed in neoplastic cells from 5/8 PTLD+ primates and 2 hyperplastic lymph nodes from 2 PTLD+ primates (control). EBNA-1 expression was demonstrated in all PTLD+ specimens with a 98.6% identity with reference cynomolgus sequences stored in GenBank, while no expression was found in controls. Four different RT-PCR assays failed to detect LMP-1 in all specimens (fig. 2). This report identifies in details the pathological features of PTLD in cynomolgus