Transcriptional analysis of immune-related genes in dendritic cells from hepatitis B surface antigen (HBsAg)-positive transgenic mice and regulation of Fc gamma receptor IIB by HBsAg-anti-HBs complex

To study the gene expression profiles in dendritic cells (DCs) from a hepatitis B surface antigen (HBsAg) positive host, transcriptional analysis of bone marrow -derived DCs from a lineage of HBsAg transgenic mice (#59) was compared to DCs from normal mice. Among the immune-related genes, 12 were up-regulated, and 14 were down-regulated in transgenic mice relative to those of normal mice. The up-regulated genes include genes encoding immunoglobulin, histocompatibility 2 (K region), and several complement component genes, while the down-regulated genes include the TAP1 (transporters associated with antigen processing gene-1), interferon induced gene (Ifi203), chemokine (C-X-C) ligands and leukocyte-immunoglobulin-like genes, Lck-interacting transmembrane adaptor genes and histocompatibility 2 (Q region and T region). Since an immunogenic complex containing HBsAg-anti-HBs has been used as a therapeutic vaccine for clinical trial in chronic hepatitis B patients, DCs from #59 were incubated with immunogenic complex compared to those incubated with HBsAg alone. The immune-related six genes up-regulated with immunogenic complex treatment were Fcgr2b, Cxcl2, Fth1, Clec4n, Lilrb4, and Dbh, with Fcgr2b (Fc gamma receptor IIB) being the highest up-regulated gene. Interestingly, levels of Fcgr2b were found up-regulated in patients with chronic hepatitis B undergoing immunogenic complex immunization, which returned to baseline when immunization was discontinued. In conclusion, by transcriptional analysis, immunogenic complex induced up-regulation of Fcgr2b expression both in dendritic cells from an HBsAg transgenic mouse model and peripheral B cells from patients with chronic hepatitis B, which indicates that Fcgr2b is one of the key molecules up-regulated by immunogenic complex.