This is a phase II, multicentric, open-label, non-randomized study, evaluating the efficacy of a single injection of Pegfilgrastim (6mg) administered at day 3 of each cycle of R-ACVBP regimen during 4 cycles in patients aged 18 to 60 years with previously untreated CD20+ diffuse large B-cell lymphoma presenting at least 2 adverse prognostic factor of the age-adjusted international prognostic index (Aa-IPI), and eligible for transplant.