title: Human peripheral blood B cell subpopulations: surface IgD+ cells respond to pokeweed mitogen with plasma cell differentiation.
abstract: Human peripheral blood (PB) mononuclear cells were depleted of T cells and subsequently of monocytes by counterflow centrifugation. The resulting B cell enriched fraction contained less than 3% T cells, 1 +/- 1% monocytes and 71 +/- 6% B cells. Approximately 56% of the B cells carried surface IgM (sIgM) and sIgD, the remaining 44% carried only one isotype (IgG, IgA, IgM or IgD). Using anti-delta or anti-mu-coated Ox red blood cells (OxRBC) the B cell enriched fraction was separated into a sIgD+ or sIgM+ and sIgD- or sIgM- fraction. The sIgD+ as well as the sIgM+ fraction responded (partially) to pokeweed mitogen (PWM) with plasma cell differentiation into cytoplasmic IgM (cIgM) containing cells. Cytoplasmic IgD+ cells were occasionally found in the sIgD+ or sIgM- fraction, but never in the sIgM+ fraction. Cells containing cIgG or cIgA were only found after stimulation of the sIgM- or sIgD- fraction, the latter also produced cIgM+ cells. In a second separation step of the sIgD- and sIgM- fraction with anti-alpha or anti-gamma-coated OxRBC it was shown that the cIgA+ and cIgG+ cells were derived from B cells expressing only sIgA or sIgG respectively. In conclusion, two major B cell subpopulations can be found in PB: a sIgM+D+ fraction, which gives rise to only cIgM+ plasma cells after PWM stimulation and a second population of B cells which express one heavy-chain isotype on their surface. These cells not only differentiate on PWM stimulation, but they also show a strong proliferative response.
mesh_terms: D000328:Adult; D001402:B-Lymphocytes / Q000145:classification* / Q000276:immunology; D002454:Cell Differentiation; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007072:Immunoglobulin D / Q000032:analysis*; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D011043:Pokeweed Mitogens / Q000276:immunology; D011947:Receptors, Antigen, B-Cell / Q000032:analysis*; D012397:Rosette Formation
chemical_list: D007070:Immunoglobulin A; D007072:Immunoglobulin D; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011043:Pokeweed Mitogens; D011947:Receptors, Antigen, B-Cell