EPSTEIN BARR VIRUS (EBV) EXPRESSION AND LATENCY PATTERN IN PEDIATRIC DIFFUSE LARGE B CELL LYMPHOMA (DLBCL). ITS EFFECT ON TREG CELLS MICROENVIRONMENT

COHEN M; DE MATTEO E; LARA J; AVERSA L; PRECIADO MV; CHABAY P

Auckland

Congreso; 43rd Congress of the International Sociaty of Pediatric Oncology (SIOP); 2011

EBV incidence in adult DLBCL ranges from 5 to 15 percent, mostly associated with patients older than 50 years. In 2008 the WHO classification included EBV positive DLBCL of the elderly, in patients >50 years which displayed type II or III EBV latency patterns. Data on pediatric DLBCL patients are quite limited. An increased number of Treg cells were described in EBV positive Hodgkin lymphoma, but this scenario is not described in DLBCL. Aims: To study EBV association and latency pattern in pediatric DLBCL, and to characterize EBV effects on microenvironment Treg population. Methods: We analyzed 25 DLBCL pediatric patients (5 immunocompromissed), age range 2 to 16 ys (median: 7ys), male:female ratio 12:13. EBV expression was evaluated by EBERs in situ hybridization, and LMP1, LMP2a, FoxP3 and CD3 expression was assessed by immunohistochemistry in formalin fixed-paraffin embedded lymph node biopsies. FoxP3 was expressed as (n FoxP3positive cells/field)/(n CD3 cells/field)× 100. Results: Ten out of 25 cases (40%) were EBERs positive, 6/20 (30%) immunocompetent and 4/5 (80%) immunocompromissed. Latency pattern was EBERs+, LMP1-, LMP2a- in 4/10 (40%) cases and EBERs+, LMP1+, LMP2a negative in 6/10 (60%) cases, 4/6 (67%) LMP1positive cases were immunocompromissed. EBV expression was not statistically associated with CD3 and FoxP3 markers (p=0.1107 and p=0.8492 respectively). In Kaplan Meier survival analysis, 5 ys event-free survival (5ys EFS) in EBV+ cases was 42%, versus 79% in EBV- cases, but this difference was not statistically significant (p=0.1431). Conclusions: EBV association in our series was higher than that for adult