Rituximab inhibits Kv1.3 channels in human B lymphoma cells via activation of FcyRIIB receptors

• Type of Material: Article
• Authors: Li-Hua Wang, Harbin Medical University; Ning Wang, Emory University; Xiao-Yu Lu, Emory University; Bing-Chen Liu, Emory University; Murali K. Yanda, Emory University; John Z. Song, Emory University; Helena M. Dai, Emory University; Yu-Liang Sun, Emory University; Hui-Fang Bao, Emory University; Douglas C Eaton, Emory University; Heping Ma, Emory University
• Language: English
• Date: 2012-02
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2011 Elsevier B.V. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.bbamcr.2011.11.012
• Title of Journal or Parent Work: BBA - Molecular Cell Research
• ISSN: 0167-4889
• Volume: 1823
• Issue: 2
• Start Page: 505
• End Page: 513
• Grant/Funding Information: This work was supported by Department of Health and Human Services, National Institutes of Health grants (5R01-DK067110 to He-Ping Ma and 5R37-DK037963 to Douglas C. Eaton).
• Keywords: Fc receptor; Voltage-dependent potassium channel; Patch-clamp technique; Confocal microscopy; Rituximab; Apoptosis
• Research Categories: Biology, Molecular; Biology, Physiology

Abstract

Kv1.3 channels play an important role in modulating lymphocyte proliferation and apoptosis. We hypothesized that Kv1.3 channels in B lymphocytes might be regulated by rituximab, an antibody to CD20, a drug for treatments of B-cell lymphomas and autoimmune diseases. Using both whole-cell and cell-attached patch-clamp techniques, we found that rituximab inhibited Kv1.3 channels in Daudi human B lymphoma cells by promoting the channel inactivation at a concentration which was much greater than that required for activation of CD20. The effect of rituximab on Kv1.3 channels was abolished after selective blockade of FcγRIIB receptors with anti-FcγRIIB antibody. Western blot experiments showed that Daudi B cells expressed both Kv1.3 channel and the low affinity Fc receptor, FcγRIIB, which could be activated by the Fc region of rituximab. In contrast, normal lymphocytes expressed less Kv1.3 channels with faster inactivation. Confocal microscopy and flow cytometry data showed that rituximab induced apoptosis of Daudi B cells and that the effect was attenuated by blockade of FcγRIIB receptors and partially mimicked by inhibition of Kv1.3 channels. These results suggest that in addition to previously described complement-dependent cytotoxicity, rituximab also induces apoptosis of malignant B lymphocyte by stimulating FcγRIIB receptors and inhibiting Kv1.3 channels.