The neonatal Fc receptor (FcRn) plays key roles in IgG and albumin homeostasis, maternal IgG transport, and antigen presentation of IgG-opsonized antigens. to wild-type controls. bFcRn expression in splenic B cells was also detected and that may also contribute to the enhanced B cell activation. Finally, we demonstrated that these Tg mice developed efficient immune response against very low dose of antigen, reflecting another important practical benefit of these Tg mice. data suggested that overexpression of the bFcRn in APCs results in augmented Ag presentation leading to increased number of Ag-specific B cells in the bFcRn Tg mice. Yet, the augmented antigen presentation has not been analyzed in the secondary lymphoid organs of these Tg mice, and thus the relationship between bFcRn overexpression and the increased number of antigen-specific B cells buy LY2608204 during the humoral immune response still had to be confirmed. Therefore, we first analyzed the architecture of the spleen and identified the bFcRn-positive cells in the secondary lymphoid organs of the bFcRn Tg mice comparing them to the expression pattern of the mouse buy LY2608204 FcRn (mFcRn) that had been reported for phagocytic cells and APCs (14C18). This issue is important as the bFcRn expression is regulated by its own regulatory elements in these Tg mice (6) that are similar to its mouse and human counterparts with some differences. Notably, we found upregulation of the bFcRn by NFB in the spleen and peritoneal Ms (19) similarly to the human FcRn (hFcRn) (20), while this has not been reported for the mFcRn (21). Despite the difference of cytokine inducibility, mFcRn and hFcRn are considered to be expressed in the same cell types and thus mouse is a well-established model for analyzing the distribution and function of the buy LY2608204 hFcRn. Nevertheless, there is at least one exception from this general concept as mFcRn is expressed only in newborn enterocytes, while hFcRn is expressed in these cells throughout life (4), suggesting careful analysis of the expression and function of the transgenic bFcRn in these Tg mice is salutary. We also analyzed the Ag presentation efficiency of the splenic APCs by immunizing Tg and Rabbit Polyclonal to DOK5 wt mice with ovalbumin (OVA) and studied recall activation of T cells from unsorted splenocytes of these mice. Then, we determined germinal center (GC) size distributions and kinetics of their formation in the spleen followed by trinitrophenyl (TNP)-KLH immunization. Finally, the efficiency of the Ag-specific IgG antibody responses against low-dose antigen was evaluated. Materials and Methods Animals We used hemizygous transgenic mice that carry five copies of the bFcRn -chain encoding gene (bovine FCGRT) in addition to the endogenous mouse FCGRT gene on BALB/c genetic background [BALB/c_Tg5_bFCGRT(19); 19 refers to the founder line] that we have previously generated (9). Wt BALB/c mice were littermates of the transgenic animals resulted from hemizygous breeding. Mice were kept under specified pathogen free (SPF) conditions in individual ventilation cages (IVC) in the animal house of the Department of Immunology, E?tv?s Lornd University, Budapest, Hungary. Treatments of mice in this study were carried out in strict accordance with the recommendations in the Guide of the Institutional Animal Care and Ethics Committee at E?tv?s Lornd University that operated in accordance with permissions 22.1/828/003/2007 and XIV-I-001/517-4/2012 issued by the Food Chain Safety buy LY2608204 and Animal Health Directorate of the Government Office of Pest County, Hungary. Immunohistochemical localization of the bovine and mouse FcRn in the spleen Ten-week-old female bFcRn transgenic and wt BALB/c mice were immunized intraperitoneally (i.p.) with 50?g keyhole limpet hemocyanin (KLH; Sigma-Aldrich) conjugated to TNP in complete Freund adjuvant (CFA), boosted 3?weeks later with 25?g TNP-KLH in incomplete Freund adjuvant (IFA), and euthanized 3?days thereafter. Spleens of non-immunized and immunized mice were frozen in liquid N2, embedded in Killik cryostat embedding medium (Bio-Optica, Milano, Italy), and 10C15?m sections were made and fixed with acetone. Before staining, sections were blocked by 5% BSA for 20?min at RT. Cell populations were identified with Alexa Fluor 568-labeled anti-Thy-1 (clone IBL-1), Cy3-labeled anti-MARCO (clone IBL-12), and MOMA (sialoadhesin/CD169, clone IBL-13) mAbs, that were developed in our laboratory (22C24). Anti-B220 (clone RA3-6B2), F4/80, Gr-1/Ly-6C/G (clone RB6-8C5), MAdCAM-1 (clone MECA-367) were obtained from the American.