Expression of complement regulatory proteins: CD46, CD55, and CD59 and response to rituximab in patients with CD20+ non-Hodgkin's lymphoma.

Rituximab is an anti-CD20 humanized monoclonal antibody widely used in the treatment of B-cell non-Hodgkin's lymphomas (NHLs). Its mechanism of action is related with complement function-complement mediated cytotoxicity. CD46, CD55, and CD59 are complement regulatory proteins. The aim of this study was to analyze expression of complement inhibitors CD46, CD55, and CD59 in patients with CD20(+) NHLs treated with rituximab combined with chemotherapy. A total of 27 patients with CD20(+) NHLs were evaluated (13 females and 14 males). The median age of patients was 56 years. All patients were examined before treatment with rituximab. Expression of CD46, CD55, and CD59 was determined by two-color flow cytometry. A total of 15 patients achieved complete response (CR), 5 patients achieved partial response, and 7 patients had no or minimal response (NR) after rituximab therapy. We observed that expression of CD46 and CD59 were higher in patients with CR than in group with NR. Expression of CD55 and CD59 were higher in patients with bulky disease. In conclusion level of expression of CD46, CD55, and CD59 could be clinically helpful to predict the response to rituximab therapy.