title: CD5+ B cells are preferentially expanded in rabbit appendix: the role of CD5 in B cell development and selection.
abstract: Although only a small proportion of mouse and human B cells are CD5(+), most adult rabbit B cells express CD5. However, CD5 was not detectable on the majority of B cells in neonatal appendix 1 and 3days after birth. Cell trafficking studies demonstrated that CD5(+) and CD5(-) CD62L(+) B cells from bone marrow migrated into appendix. There, CD5(+) B cells were preferentially expanded and predominated by approximately 2weeks of age. In mutant ali/ali rabbits, VHa2(+) B cells develop through gene conversion-like alteration of rearranged VH genes upstream of deleted VH1a2. Correlated appearance of individual CD5(+) germinal centers and VHa2(+) B-cells in mutant appendix suggests that CD5 binding positively selects cells with a2(+) framework regions that bind CD5. Following negative and positive selection, cells with diversified rearranged heavy- and light-chain sequences exit appendix, migrate to peripheral tissues and constitute the preimmune repertoire of CD5(+) B cells that encounter foreign antigens.
authors.affiliation: Laboratory of Immunology, NIAID, National Institutes of Health, Bethesda, MD 20892-1892, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Pospisil
authors.forename: Cornelius B
authors.initials: CB
authors.lastname: Alexander
authors.forename: Harold
authors.initials: H
authors.lastname: Obiakor
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Sinha
authors.forename: Rose G
authors.initials: RG
authors.lastname: Mage
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001065:Appendix / Q000166:cytology / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D001483:Base Sequence; D001853:Bone Marrow / Q000276:immunology; D018956:CD5 Antigens / Q000502:physiology*; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D005803:Genes, Immunoglobulin; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region / Q000235:genetics; D019041:L-Selectin; D008969:Molecular Sequence Data; D011817:Rabbits / Q000254:growth & development / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology
chemical_list: D018956:CD5 Antigens; D007143:Immunoglobulin Heavy Chains; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region; D019041:L-Selectin