Background and purpose: The clinical relevance of HBV infection with respect to diffuse large B cell lymphoma(DLBCL) patients and immune patterns of T lymphocyte subsets during chemotherapy remains unclear. This study aimed to identify the characteristics of T-cell mediated immunity in DLBCL patients with HBV infection

thereafter

to explore the possible cell-mediated immune mechanisms of HBsAg positive HBV infection on the survival of DLBCL. Methods: A total of 294 newly diagnosed DLBCL patients were enrolled in this cohort study. Four-color flow cytometric method was used to enumerate the absolute number of CD3+

CD4+

CD8+ T lymphocytes and the CD4+/CD8+ ratio in peripheral blood samples

at the onset of disease

2-4

4-6 and 6-12 months after the initiation of chemotherapy

individually. Results: The absolute number of CD3+

CD4+

CD8+ T lymphocytes in both groups were similar at the onset of disease; the count of CD4+ lymphocytes was lower in HBsAg positive group during 2 to 4 months after the initiation of chemotherapy

compared with that in the HBsAg negative group. During 4 to 12 months after chemotherapy

the CD4+/CD8+ ratio in peripheral blood samples was significantly lower in HBsAg positive group. Conclusion: For newly diagnosed DLBCL patients who received chemotherapy

the dynamic nature of cell mediated immune response was characterized as a low counts of CD4+ T lymphocyte during the first several cycles of chemotherapy followed by a decreased circulating CD4+/CD8+ ratio. Depressions of cell immunity after chemotherapy in HBsAg positive DLBCL patients were greater and prolonged.