Rituximab Treatment in Hepatitis C Infection: An In Vitro Model to Study the Impact of B Cell Depletion on Virus Infectivity

Zania Stamataki,Jane A Mckeating,David H Adams,Samantha Tilakaratne,Jianming Qiu

doi:10.1371/journal.pone.0025789

Abstract

Hepatitis C virus (HCV) infected patients with vasculitis are often treated with the B-cell-depleting anti-CD20 antibody rituximab. Treatment reduces the cryoglobulins that cause vasculitis, yet it also leads to a transient increase in liver enzymes and HCV genomic RNA in the periphery. The mechanism underlying the increased viral load is unclear and both direct and indirect roles have been proposed for B cells in HCV infection. We previously reported that HCV can associate with B cells and can trans-infect hepatocytes. We established an in vitro assay to study the effect(s) of rituximab on B cell-associated HCV infectivity. Rituximab-mediated lysis of B cells in vitro increases the level of infectious HCV released from B cells. Our results, using a model where virus does not replicate in B cells, recapitulate observations seen in patients and may explain in part the rapid increase in blood HCV RNA observed after rituximab treatment.

Highlights

Hepatitis C virus (HCV) infection predominantly affects the liver but extrahepatic manifestations have been reported [1,2]
Use of primary B cells from peripheral blood of healthy donors as targets instead of L3055 cells yielded comparable results, this may not reflect the ability of B cells in vivo to capture virus
It is worth noting that L3055 B cells used as rituximab targets, as well as B cells from healthy donors, were not specific for HCV; we previously demonstrated that primary Peripheral blood mononuclear cells (PBMC)-derived B cells and L3055 cells bind comparable amounts of HCV that replicates in cell culture (HCVcc) RNA as measured by quantitative RT-PCR [17]

Summary

Introduction

HCV infection predominantly affects the liver but extrahepatic manifestations have been reported [1,2]. Patients who present with symptoms of vasculitis caused by type II cryoglobulinaemia can benefit from treatment with the chimeric monoclonal anti-CD20 antibody rituximab, which depletes B cells in the circulation. Pre-B cells, immature, mature and activated B cells all express CD20 and are susceptible to antibody-dependent lysis [5]. The main modes of rituximab action include antibodydependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) (Figure 1), apoptosis and phagocytosis have been implicated in B cell depletion [7,8,9]. Treatment reduces the level of antibodies that drive cryoglobulin formation and alleviates the clinical symptoms of vasculitis, yet treatment is often associated with a transient increase in liver enzymes and peripheral HCV viral load [10,11]

Methods

Results

Conclusion