The mechanism of anti-CD20–mediated B cell depletion revealed by intravital imaging
Fabricio Montalvao, … , Nico Van Rooijen, Philippe Bousso
Fabricio Montalvao, … , Nico Van Rooijen, Philippe Bousso
Published November 1, 2013
Citation Information: J Clin Invest. 2013;123(12):5098-5103. https://doi.org/10.1172/JCI70972.
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The mechanism of anti-CD20–mediated B cell depletion revealed by intravital imaging

Abstract

Anti-CD20 Ab therapy has proven successful for treating B cell malignancies and a number of autoimmune diseases. However, how anti-CD20 Abs operate in vivo to mediate B cell depletion is not fully understood. In particular, the anatomical location, the type of effector cells, and the mechanism underlying anti-CD20 therapy remain uncertain. Here, we found that the liver is a major site for B cell depletion and that recirculation accounts for the decrease in B cell numbers observed in secondary lymphoid organs. Using intravital imaging, we established that, upon anti-CD20 treatment, Kupffer cells (KCs) mediate the abrupt arrest and subsequent engulfment of B cells circulating in the liver sinusoids. KCs were also effective in depleting malignant B cells in a model of spontaneous lymphoma. Our results identify Ab-dependent cellular phagocytosis by KCs as a primary mechanism of anti-CD20 therapy and provide an experimental framework for optimizing the efficacy of therapeutic Abs.

Authors

Fabricio Montalvao, Zacarias Garcia, Susanna Celli, Béatrice Breart, Jacques Deguine, Nico Van Rooijen, Philippe Bousso

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Figure 2

Tracking KCs using the MAFIA mouse model.

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Tracking KCs using the MAFIA mouse model. (A) Mice were injected intrave...
(A) Mice were injected intravenously with clodronate (lip-CL) or control liposomes (lip-PBS). After 24 hours, depletion of KCs (F4/80+CD11blo) by lip-CL was confirmed by flow cytometry. Numbers in A and D correspond to the percentage of cells falling in the indicated gate. (B) B cell depletion following anti-CD20 injection was quantified as in Figure 1 in the blood in mice treated with clodronate or control liposomes. ***P < 0.001. (C) Flow cytometric analysis of liver cells in MAFIA mice. Data are gated on CD45+ cells. Red and black histograms were obtained using the corresponding gates shown in the leftmost panel. (D) MAFIA mice were injected intravenously with clodronate or control liposomes. After 24 hours, liver cells were analyzed by flow cytometry. (E) Sessile GFP+ cells in the livers of MAFIA mice correspond to KCs. MAFIA mice were injected intravenously with PE-conjugated anti-F4/80 Ab and subjected to intravital imaging of the liver 10 minutes later. Time-lapse images showing that sessile spindle-shaped GFP+ cells with typical KC morphology were all stained with F4/80 Ab. In contrast, motile GFP+ cells (indicated by white arrowheads) were all F4/80–. Scale bar: 10 μm.