Characterization of phenotypically distinct B-cell subsets and receptor-stimulated mitogen-activated protein kinase activation in human cord blood B cells.
Human cord blood (CB) is a valuable source of hematopoietic stem cells, but clinical reports have indicated slow recovery of B-cell development and function after CB transplantation. To investigate the basis of these B-cell defects in reconstitution, we characterized B cells purified from CB. We compared B-cell receptor activation and B-cell subsets in CB, bone marrow (BM), and peripheral blood (PB). We found that in CB B cells activation of extracellular signal-regulated kinase (ERK) and p38 following ligation of CD40 but not of the B-cell antigen receptor (BCR) was inefficient. The patterns of expression of CD5, CD34, and CD40 in the B-cell population of CB were similar to those in PB rather than in BM. The B cells in CB contained an increased proportion of B cells expressing a high level of CD24 and a low proportion of B cells expressing CD27, pointing to the presence of circulating CD24high immature transitional and CD27(-) naive B cells. CD40-mediated activation of ERK and p38 was also minimal in these B cells of CB. These findings may account for the functional defects of B cells in transplanted CB.
Ha
Yun Jung
YJ
Division of Life and Pharmaceutical Sciences, Ewha Womans University, 11-1 Daehyun-Dong, Seodaemun-Gu, Seoul 120-750, Korea.
Mun
Yeung-Chul
YC
Seong
Chu-Myong
CM
Lee
Jong Ran
JR
D000328:Adult; D018952:Antigens, CD34 / Q000276:immunology / Q000378:metabolism; D016175:B-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D001853:Bone Marrow / Q000276:immunology / Q000378:metabolism; D019013:CD40 Antigens / Q000276:immunology / Q000378:metabolism; D018956:CD5 Antigens / Q000276:immunology / Q000378:metabolism; D004789:Enzyme Activation; D005312:Fetal Blood / Q000276:immunology / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology / Q000378:metabolism; D008213:Lymphocyte Activation; D020929:Mitogen-Activated Protein Kinase Kinases / Q000276:immunology / Q000378:metabolism*; D010641:Phenotype; D011947:Receptors, Antigen, B-Cell / Q000276:immunology / Q000378:metabolism*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000276:immunology / Q000378:metabolism
D018952:Antigens, CD34; D019013:CD40 Antigens; D018956:CD5 Antigens; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D020929:Mitogen-Activated Protein Kinase Kinases