title: Memory B lymphocytes migrate to bone marrow in humans.
abstract: IgM-bearing B lymphocytes with mature phenotype (CD10- CD24(lo) IgD+) are acquired after birth in the bone marrow of humans. These B cells are defined here as relatively large, nondividing lymphocytes, variable proportions of which express cell surface molecules indicative of relatively recent activation. Analysis of V(H)5(2) (heavy chain variable region) gene transcripts indicated point mutations throughout the Ig variable region from the mature IgM+ B population but not from the immature B cells in the bone marrow. The mutations were concentrated in the complementarity determining regions, and amino acid substitutions were favored over silent mutations, findings indicative of antigen selection within germinal centers in peripheral lymphoid tissues. The V(H) sequence analysis also revealed the existence of clonal relatives in individual bone marrow samples. These antigen-experienced lymphocytes did not secrete Ig spontaneously but could be induced to do so in vitro. The data suggest that a subpopulation of memory B lymphocytes generated during antigen responses recirculates to the bone marrow in humans.
authors.affiliation: Department of Medicine, Division of Clinical and Developmental Immunology, Howard Hughes Medical Institute, University of Alabama, Birmingham 35294-3300, USA.
authors.forename: E
authors.initials: E
authors.lastname: Paramithiotis
authors.forename: M D
authors.initials: MD
authors.lastname: Cooper
mesh_terms: D000328:Adult; D000367:Age Factors; D000921:Antibody-Producing Cells; D015703:Antigens, CD / Q000032:analysis; D016175:B-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology*; D001483:Base Sequence; D001853:Bone Marrow / Q000276:immunology*; D001854:Bone Marrow Cells; D002465:Cell Movement; D003001:Cloning, Molecular; D005333:Fetus / Q000166:cytology / Q000276:immunology; D006801:Humans; D007072:Immunoglobulin D / Q000032:analysis; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007075:Immunoglobulin M / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007156:Immunologic Memory; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D017422:Sequence Analysis, DNA
chemical_list: D015703:Antigens, CD; D007072:Immunoglobulin D; D007143:Immunoglobulin Heavy Chains; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region