A New Memory CD27-IgG+ B Cell Population in Peripheral Blood Expressing VH Genes with Low Frequency of Somatic Mutation.

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BlankA New Memory CD27-IgG+ B Cell Population in Peripheral Blood Expressing VH

Genes with Low Frequency of Somatic Mutation.

JF Fecteau, G Cote, and S Neron

J. Immunol., September 15, 2006; 177(6): 3728-36.

Héma-Québec, Recherche et Développement, Sainte-Foy, Quebec, Canada.

In humans, up to 40% of peripheral B cells express CD27 and have hypermutated

variable regions in their Ig genes. The CD27(+) B cells are considered to be

derived from germinal center following specific antigenic stimulation. Actually,

somatic hypermutation in Ig genes and CD27 expression are hallmarks of memory B

cells. However, the blood IgM(+)IgD(+)CD27(+) B cells were recently associated

to splenic marginal zone B cells and proposed to be a subset distinct from

germinal center-derived memory B cells showing premutated Igs. The results

presented herein further weaken this bona fide association because B cells

expressing surface IgG, but not CD27, were found in human blood. Representing

1-4% of all peripheral B cells and approximately 25% of the IgG(+) blood B

cells, this population expressed mutated IgG genes showing antigenic selection

characteristics but with lower mutation frequencies than that of CD27(+)IgG(+) B

cells. However, their morphology and phenotype were similar to that of

CD27(+)IgG(+) cells. Interestingly, the proportion of IgG2 over IgG3 transcripts

was opposite in CD27(-)IgG(+) and CD27(+)IgG(+) cells, suggesting distinct

functions or origins. Overall, these findings extend the memory B cell reservoir

beyond the CD27(+) compartment and could provide further insights into B cell

disorders of unknown etiology.

Publication Type:

a.. Journal article

PMID: 16951333