Dose Dense Chemotherapy + Rituximab +/-Intensified High Dose Chemoimmunotherapy With Support of Peripheral Autologous Stem Cell in Diffuse Large B-Cell Lymphoma

Inclusion Criteria: 1. Age 18-60; 2. Histological confirmed diagnosis of Diffuse Large B-Cell Lymphoma CD20+ (newly diagnosis or shifted from low grade NHL and not previously treated) or of Follicular Lymphoma grade III according to REAL/WHO Classification. 3. Advanced stage II, stage III and stage IV with at least two aa-IPI risk factors. 4. Age-adjusted IPI 2-3. 5. ECOG performance status 0-2. 6. LVEF\>45%, measured with echocardiography. 7. Normal hepatic, renal and pulmonary functions. 8. HIV, HCV and HBV negativity. 9. HCV+ admitted only in histologically confirmed absence of replication marks. 10. Positive serology for HBV (occult carriers: AntiHBcAg+, HbsAg-, AntiHBsAg+/-) admitted only upon negativity of weakly positive HBV-DNA test. 11. Life expectancy \> 3 months. 12. Negative pregnancy test. 13. Written Informed Consent. Exclusion Criteria: 1. Histological diagnosis of: * Lymphoblastic NHL * Burkitt's Lymphoma * CD 20 negative B-cell Lymphoma * grade I-IIIa Follicular Lymphoma * Mantle Cell Lymphoma * Primary mediastinal NHL with exclusively intrathoracic localization. 2. Age \> 60 3. Stage I disease 4. Age-adjusted IPI 0-1 5. ECOG-PS\>3, if not related to Lymphoma 6. Renal impairment (creatinine\>1,2 mg/dl or creatinine clearance \< 60ml/min) 7. Hepatic impairment (AST/ALT or bilirubin \> 2,5 times normal limit, unless due to Lymphoma) 8. HIV positive patients and/or with HBV or HCV active infection(documented by HBV-DNA and HCV-RNA positive tests) 9. Clinically significant secondary cardiovascular disease e.g. uncontrolled hypertension (resting diastolic blood pressure \> 115 mmHG), uncontrolled multifocal cardiac arrhythmias, symptomatic angina pectoris or congestive cardiac failure NYHA class III-IV 10. LFEV\<45% 11. Severe diabetes mellitus difficult to control with adequate insulin therapy 12. Severe chronic obstructive pulmonary disease with hypoxemia 13. Active bacterial, viral of fungal infection requiring systemic therapy 14. Concurrent thrombohemolytic disease 15. HIV positivity 16. HBV positivity 17. Positive serology for HBV (occult carriers: AntiHBc+, HbsAg-, AntiHbs+/-) with positive HBV-DNA test 18. HCV positivity in presence of replication marks (HCV+, CRP+, AST 1,5-2 times normal ranges) 19. CNS localization of disease 20. Prior (during last 3 years) or concurrent malignancy except adequately treated basal cell carcinoma of the skin or carcinoma in situ of the cervix or early stage prostate cancer not requiring systemic therapy, or early breast cancer treated with surgery alone. Any other co.existing medical condition that would preclude study therapy administration 21. Pregnancy or breast-feeding women 22. Inability of the patient to give her/his informed consent 23. Known hypersensitivity or anaphylactic reaction to murine antibodies or proteins