Studies of in vitro activated CD5+ B cells.
Human B lymphocytes undergo distinct phenotypic changes following activation with antigen and polyclonal mitogens. Increasing interest has focused on the unique subpopulation of B cells that expresses the CD5 antigen. In this study, we examined the signals that induce the expression of CD5 on normal splenic B cells. Only 12-O-tetradecanoylphorbol-13-acetate (TPA) induced CD5 expression on highly purified splenic B cells, whereas anti-immunoglobulin (anti-Ig), Epstein-Barr virus, anti-CD20, recombinant interleukin-1 (rIL-1), rIL-2, rIL-4, recombinant interferon-gamma (rINF-gamma), and B-cell growth factor all failed to induce CD5 expression. The expression of CD5 was detected on the cell surface by 48 hours and decreased by 96 hours. Dual-fluorochrome analysis demonstrated that the CD5+ B cells coexpressed the B-cell activation antigens B5, IL-2 receptor, and CD23, thereby providing phenotypic evidence that this B-cell subpopulation is activated. In vitro studies of dual-fluorochrome-sorted, TPA-stimulated splenic B cells demonstrated significantly greater tritiated thymidine incorporation and Ig secretion by the CD20+ CD5- cells than by the CD20+ CD5+ subset. These phenotypic and functional studies are consistent with the notion that TPA-induced CD5+ B cells are a subset of in vitro activated B lymphocytes.
Freedman
A S
AS
Division of Tumor Immunology, Dana-Farber Cancer Institute, Boston, MA 02115.
Freeman
G
G
Whitman
J
J
Segil
J
J
Daley
J
J
Nadler
L M
LM
D018951:Antigens, CD20; D000944:Antigens, Differentiation, B-Lymphocyte / Q000096:biosynthesis; D001402:B-Lymphocytes / Q000145:classification* / Q000276:immunology; D002454:Cell Differentiation / Q000187:drug effects; D002469:Cell Separation; D002478:Cells, Cultured; D000939:Epitopes; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D010641:Phenotype; D013154:Spleen; D013755:Tetradecanoylphorbol Acetate
D018951:Antigens, CD20; D000944:Antigens, Differentiation, B-Lymphocyte; D000939:Epitopes; D013755:Tetradecanoylphorbol Acetate