title: Expression of human complement receptor 2 (CR2, CD21) in Cr2-/- mice restores humoral immune function.
abstract: Complement receptor type 2 (CR2, CD21) is expressed by both human and murine B cells and has been demonstrated to play a pivotal role in the humoral immune response. We have reconstituted Cr2-/- mice with an 80-kb human genomic fragment (designated P1-5) containing the full-length human CR2 (hCR2) gene. Transfection of P1-5 into the mouse A20 B cell line confirmed that it would direct expression of the hCR2 protein in mouse B cells. Immunoprecipitation analysis in these cells revealed that hCR2 coassociates with mouse CD19. After creation of transgenic mice using P1-5, we found significant expression of hCR2 on peripheral blood and splenic B cells by flow cytometric analysis. RT-PCR analysis of tissues and purified cell populations from transgene-positive mice revealed that hCR2 expression was restricted to B cells and the spleen in a pattern that matches mouse CR2. To rigorously assess the functional capabilities of hCR2, the transgene was bred onto Cr2-/- mice, which have a notable defect in response to SRBC Ag. We found that Cr2-/- mice expressing hCR2 had a substantial restoration of the humoral immune response to SRBC as compared with nontransgenic Cr2-/- littermate controls. Overall, this study suggests that hCR2 is able to substitute for mouse CR2 in the murine immune system. Therefore, hCR2-transgenic mice offer a valuable model system to further examine immunologic roles as well as structure-function relationships important for hCR2 function in primary cells in vivo.
authors.affiliation: Division of Rheumatology, Departments of Medicine and Immunology, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Marchbank
authors.forename: C C
authors.initials: CC
authors.lastname: Watson
authors.forename: D F
authors.initials: DF
authors.lastname: Ritsema
authors.forename: V M
authors.initials: VM
authors.lastname: Holers
mesh_terms: D000818:Animals; D000910:Antibodies, Heterophile / Q000096:biosynthesis; D000917:Antibody Formation / Q000235:genetics*; D018941:Antigens, CD19 / Q000378:metabolism; D015478:Antigens, Heterophile / Q000008:administration & dosage / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D002999:Clone Cells; D003433:Crosses, Genetic; D004912:Erythrocytes / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology*; D005818:Genetic Engineering; D006801:Humans; D007114:Immunization; D051379:Mice; D008822:Mice, Transgenic; D017464:Receptors, Complement 3d / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D012756:Sheep; D014162:Transfection / Q000276:immunology
chemical_list: D000910:Antibodies, Heterophile; D018941:Antigens, CD19; D015478:Antigens, Heterophile; D017464:Receptors, Complement 3d