Human blood IgM “memory” B cells are circulating splenic marginal zone B cells harboring a prediversified immunoglobulin repertoire

S Weller, MC Braun, BK Tan, A Rosenwald, C Cordier… - Blood, 2004 - ashpublications.org
S Weller, MC Braun, BK Tan, A Rosenwald, C Cordier, ME Conley, A Plebani
Blood, 2004ashpublications.org
The human peripheral B-cell compartment displays a large population of immunoglobulin M–
positive, immunoglobulin D–positive CD27+ (IgM+ IgD+ CD27+)“memory” B cells carrying a
mutated immunoglobulin receptor. By means of phenotypic analysis, complementarity-
determining region 3 (CDR3) spectratyping during a T-independent response, and gene-
expression profiling of the different blood and splenic B-cell subsets, we show here that
blood IgM+ IgD+ CD27+ cells correspond to circulating splenic marginal zone B cells …
The human peripheral B-cell compartment displays a large population of immunoglobulin M–positive, immunoglobulin D–positive CD27+ (IgM+IgD+CD27+) “memory” B cells carrying a mutated immunoglobulin receptor. By means of phenotypic analysis, complementarity-determining region 3 (CDR3) spectratyping during a T-independent response, and gene-expression profiling of the different blood and splenic B-cell subsets, we show here that blood IgM+IgD+CD27+ cells correspond to circulating splenic marginal zone B cells. Furthermore, analysis of this peripheral subset in healthy children younger than 2 years shows that these B cells develop and mutate their immunoglobulin receptor during ontogeny, prior to their differentiation into T-independent antigen-responsive cells. It is therefore proposed that these IgM+IgD+CD27+ B cells provide the splenic marginal zone with a diversified and protective preimmune repertoire in charge of the responses against encapsulated bacteria.
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