Human IgM+IgD+ B cells, the major B cell subset in the peripheral blood, express V kappa genes with no or little somatic mutation throughout life.
Peripheral blood B cells of a 67-year-old person were separated into IgM+IgD+, IgM+IgD-, and IgM-IgD- subsets, and nucleotide sequences of expressed immunoglobulin light chain variable (V) regions encoded by V kappa 3 and V kappa 4 gene family members were determined from amplified cDNA. V region sequences from IgM+IgD+ cells (the major B cell population in the blood) showed no or little somatic mutation (0.3%), in contrast to V kappa sequences from IgM+IgD- and IgM-IgD- B cells (2.0% and 3.9%, respectively). This suggests that in the human like in the mouse, and independently of age, somatically mutated memory B cells accumulate in the compartment of IgM-IgD- cells, whereas the IgM+IgD+ subpopulation consists of cells whose antibody repertoire is mainly determined by V region gene rearrangements and N-region insertion, at the molecular level. The somatically mutated IgM+IgD- cells may represent early descendants of IgM+IgD+ cells recruited into the memory cell compartment.
Klein
U
U
Institute for Genetics, University of Cologne, FRG.
Küppers
R
R
Rajewsky
K
K
D000368:Aged; D000595:Amino Acid Sequence; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D001483:Base Sequence; D015870:Gene Expression; D005803:Genes, Immunoglobulin; D006801:Humans; D007072:Immunoglobulin D / Q000032:analysis*; D007133:Immunoglobulin Joining Region / Q000235:genetics; D007075:Immunoglobulin M / Q000032:analysis*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation
D007072:Immunoglobulin D; D007133:Immunoglobulin Joining Region; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region; D007145:Immunoglobulin kappa-Chains