[Interleukin-2 improves the antitumor activity of Rituximab in patients with B-cell lymphoma in vitro].

Objective: To establish a method to predict therapeutic effect of Rituximab and explore the feasibility and potential of IL-2 improving antitumor activity of Rituximab with upregulated antibody-dependent cellular cytotoxicity (ADCC) in patients with B-cell lymphoma.

Methods: Eighteen B-cell lymphoma patients and 13 health volunteers entered the study. Peripheral blood mononuclear cells (PBMNC) were isolated as effector cells, and Daudi (Burkitt's lymphoma) cells as target cell, the cytotoxicity and ADCC mediated by Rituximab (10 microg/ml) of PBMNC at different E:T ratios were performed by standard 51Cr-release-assay in vitro with or without IL-2-activation. Flow cytometric analysis was performed to identify PBMNC phenotype with or without IL-2-activation.

Results: A marked decrease of cytotoxicity and Rituximab mediated ADCC in the patients as compared with that in health volunteers, the results being (5.80 +/- 1.16)%, (14.32 +/- 1.50)% and (14.29 +/- 1.68)%, (24.14 +/- 1.53)% (t = 3.693, P = 0.001 and t = 3.372, P = 0.003) respectively. The decrease was correlated with the therapeutic effect of Rituximab (r = 0.781, P < 0.05). The cytotoxicity and Rituximab mediated ADCC in the patients could be partly recovered after IL-2 activation from (5.80 +/- 1.16)%, (14.32 +/- 1.50)% to (15.43 +/- 2.62)%, (35.79 +/- 2.58)% (t = 3.35, P = 0.003 and t = 7.17, P < 0.001) respectively.

Conclusions: It may be a useful method for predicting the effect of Rituximab in B-cell lymphoma patients to analyze the cytotoxicity and ADCC of their PBMNC. The impaired activity of PBMNC could be partly recovered when IL-2 was administered before the use of Rituximab.