title: Distribution of FcRn Across Species and Tissues.
abstract: The neonatal Fc receptor (FcRn) is a major histocompatibility complex class I type molecule that binds to, transports, and recycles immunoglobulin G (IgG) and albumin, thereby protecting them from lysosomal degradation. Therefore, besides the knowledge of FcRn affinity, FcRn protein expression is critical in understanding the pharmacokinetic behavior of Fc-containing biotherapeutics such as monoclonal antibodies. The goal of this investigation was to achieve for the first time a comparative assessment of FcRn distribution across a variety of tissues and species. FcRn was mapped in about 20 tissues including placenta from human and the most frequently used species in non-clinical safety testing of monoclonal antibodies (mouse, rat, cynomolgus monkey). In addition, the FcRn expression pattern was characterized in two humanized transgenic mouse lines (Tg32 and Tg276) expressing human FcRn under different promoters, and in the severe combined immunodeficient (SCID) mouse. Consecutive sections were stained with specific markers, namely, anti-CD68 for macrophages and anti-von Willebrand Factor for endothelial cells. Overall, the FcRn expression pattern was comparable across species and tissues with consistent expression of FcRn in endothelial cells and interstitial macrophages, Kupffer cells, alveolar macrophages, enterocytes, and choroid plexus epithelium. The human FcRn transgenic mouse Tg276 showed a different and much more widespread staining pattern of FcRn. In addition, immunodeficiency and lack of IgG in SCID mice had no negative effect on FcRn expression compared with wild-type mice.
authors.affiliation: Roche Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (SL, BJ, MBO, AH, SK).
authors.forename: Sari
authors.initials: S
authors.lastname: Latvala
authors.affiliation: Roche Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (SL, BJ, MBO, AH, SK).
authors.forename: Bjoern
authors.initials: B
authors.lastname: Jacobsen
authors.affiliation: Roche Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (SL, BJ, MBO, AH, SK).
authors.forename: Michael B
authors.initials: MB
authors.lastname: Otteneder
authors.affiliation: Roche Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (SL, BJ, MBO, AH, SK).
authors.forename: Annika
authors.initials: A
authors.lastname: Herrmann
authors.affiliation: Roche Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (SL, BJ, MBO, AH, SK).
authors.forename: Sven
authors.initials: S
authors.lastname: Kronenberg
mesh_terms: D000818:Animals; D002831:Choroid Plexus / Q000737:chemistry / Q000378:metabolism; D042783:Endothelial Cells / Q000737:chemistry / Q000378:metabolism; D020895:Enterocytes / Q000737:chemistry / Q000378:metabolism; D004848:Epithelium / Q000737:chemistry / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000032:analysis* / Q000096:biosynthesis; D006801:Humans; D007728:Kupffer Cells / Q000737:chemistry / Q000378:metabolism; D008252:Macaca fascicularis; D008264:Macrophages / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016513:Mice, SCID; D008822:Mice, Transgenic; D051381:Rats; D017208:Rats, Wistar; D011961:Receptors, Fc / Q000032:analysis* / Q000096:biosynthesis
chemical_list: D015395:Histocompatibility Antigens Class I; D011961:Receptors, Fc; C100688:Fc receptor, neonatal
keywords: FcRn; SCID mouse; cynomolgus monkey; human; humanized transgenic mice Tg32 and Tg276; immunohistochemistry; mouse; neonatal Fc receptor; rat; species comparison