Characterization of proposed human B-1 cells reveals pre-plasmablast phenotype

Abstract

B cells have been described as the human counterpart of murine B-1 B cells, but this is controversial.• Our data demonstrate a preplasmablast but not a B-1 phenotype for this population of cells.Controversy has arisen about the nature of circulating human CD20

Response: Extended analysis of microarray data does not contradict preplasmablast phenotype of human CD20+CD27+CD43+ cells

“…2 On the contrary, we feel that the analysis by Li et al 1 supports and extends our findings. Both our analysis and theirs are compatible with the notion that the putative B1 cells have a phenotype intermediate between memory B cells and plasmablasts.…”

“…2 However, this assertion contradicts the Rothstein group's previous publications in which the inability of human "B1" cells to differentiate to plasmablasts was twice claimed to distinguish B-1 cells from preplasmablasts.…”

“…In 3 studies, the 2 mutations were sequentially acquired by the same stem cell, with JAK2-V617F preceding the acquisition of BCR-ABL. [2][3][4] Another report concluded that BCR-ABL and JAK2-V617F represented 2 distinct clones. 5 Here, we studied a 56-year-old female patient diagnosed in May 2005 with JAK2-V617F-positive essential thrombocythemia (ET), normal cytogenetics, and absence of BCR-ABL ( Figure 1A).…”

Anti-Pneumococcal Capsular Polysaccharide Antibody Response and CD5 B Lymphocyte Subsets

“…Recently, Griffin et al (5) claimed the discovery of a small subset of human CD20 ϩ B cells expressing CD27 and CD43 that recap the functional characteristics of murine B-1 cells. However, controversy has arisen about the nature of these cells, and we recently showed that CD27 ϩ CD43 ϩ B cells are in fact activated cells on their way to plasma cell differentiation (6)(7)(8)(9).…”

Les lymphocytes B IgM+IgD+CD27+chez l’homme

“…Ce puissant signal de prolifération agit de concert avec l'action de cytokines ou de ligands qui stimulent la sécrétion d'anti- [14,15]. En outre, l'existence des B1 chez l'homme, du moins selon la définition proposée, est de plus en plus controversée puisque la caractérisation de ces cellules B1 présumées révèle en réalité un phé-notype préplasmablastique correspondant à un stade précoce de la différenciation plasmocytaire [16]. Il est cependant intéressant de noter que les cellules B spéci-fiques de la phosphorycholine (PC) se trouvent de façon prédominante, quoique non exclusive, parmi les cellules IgM + IgD + CD27 + [17].…”