Preferential association of hepatitis C virus with CD19+ B cells is mediated by complement system

Abstract

Extrahepatic disease manifestations are common in chronic hepatitis C virus (HCV) infection. The mechanism of HCV-related lymphoproliferative disorders is not fully understood. Recent studies have found that HCV in peripheral blood mononuclear cells (PBMCs) from chronically infected patients is mainly associated with CD19+ B cells. To further elucidate this preferential association of HCV with B cells, we used in vitro cultured virus and uninfected PBMCs from healthy blood donors to investigate the necessary serum components that activate the binding of HCV to B cells. First, we found that the active serum components were present not only in HCV carriers, but also in HCV recovered patients and HCV negative healthy blood donors and that the serum components were heat labile. Second, the preferential binding activity of HCV to B cells could be blocked by anti-complement C3 antibodies. In experiments with complement-depleted serum and purified complement proteins, we demonstrated that complement proteins C1, C2, and C3 were required to activate such binding activity. Complement protein C4 was partially involved in this process. Third, using antibodies against cell surface markers, we showed that the binding complex mainly involved CD21 (complement receptor 2), CD19, CD20, and CD81; CD35 (complement receptor 1) was involved but had lower binding activity. Fourth, both anti-CD21 and anti-CD35 antibodies could block the binding of patient-derived HCV to B cells. Fifth, complement also mediated HCV binding to Raji cells, a cultured B cell line derived from Burkitt’s lymphoma. Conclusion In chronic HCV infection, the preferential association of HCV with B cells is mediated by the complement system, mainly through complement receptor 2 (CD21), in conjunction with the CD19 and CD81 complex.

Binding of Free and Immune Complex‐Associated Hepatitis C Virus to Erythrocytes Is Mediated by the Complement System

“…Detailed descriptions of our patients and methods used for cell culture, in vitro RNA synthesis, HCV production in cell culture, conversion of plasma to serum, and peripheral blood mononuclear cell (PBMC) isolation were described in our previous studies . Ethics committees of the American Red Cross and the National Institutes of Health (NIH) approved the study protocol in accord with the Declaration of Helsinki and the study has been reviewed annually by an NIH Institutional Review Board (NIH Protocol 91‐CC‐0017).…”

“…Growth of human hepatoma cell line Huh7.5.1 and preparation of full‐length HCV1a (H77S) RNA were performed as described, with minor modifications. Briefly, 42 μg of HCV1a (H77S) full‐length RNA was transfected into 1.2 × 10 7 Huh 7.5.1 cells in two 25 × 150 mm culture dishes by using mRNA boost reagent and TranslT‐mRNA reagent (MIR2250; Mirus, Madison, Wisconsin) according to the manufacturer’s instructions.…”

“…In our standard binding assay, 3 mL of virus (1 to 3 × 10 7 genomic copies for HCV genotype 1a) was mixed with 100 μL of serum (approximately 20‐25 CH50 units) to initiate complement activation and then incubated at 25°C for 30 minutes. Next, 2 mL of erythrocytes (5 × 10 8 cells total) was added to the mixture and incubated for 15 minutes.…”

“…We and another group previously demonstrated that free HCV particles from chronically infected patients could be complement‐opsonized and bound to CR1 on B lymphocytes . Chronic HCV is associated with IC‐related diseases, such as mixed cryoglobulinemia, membranous glomerulonephritis, and non‐Hodgkin’s lymphoma.…”

Clinical and pathogenetic value of immune disruptions in manifestation of mixed cryoglobulinemia in patients with chronic hepatitis C

“…Considerable heterogeneity of the HCV structure plays a role of a factor that rises the chance of development of mechanisms of molecular mimicry between the antigenic structures of the virus of host cells. The extension of the non-organ-autoantibodies spectrum in case of mixed cryoglobulinemia gives a reason to state that the autoimmune mechanisms play a significant role in the emergence of its clinical manifestations [9,10]. According to the researches results [11][12][13] different markers of autoimmune disorders can be found in patients with CHC, among them are mixed cryoglobulines (40-74 %), RF (45-98 %), hypocomplementemia (30 %), antibodies to cardiolipin (20-44 %), antibodies to Ro (SS-A) / La(SS-B) antigen, ANA (10-52 %) and others, but their clinical value, except for cryoglobulines, is still poorly studied.…”