The A-Myb transcription factor is a marker of centroblasts in vivo

J Golay, V Broccoli, G Lamorte, C Bifulco… - The Journal of …, 1998 - journals.aai.org
J Golay, V Broccoli, G Lamorte, C Bifulco, C Parravicini, A Pizzey, NSB Thomas, D Delia…
The Journal of Immunology, 1998journals.aai.org
The A-Myb transcription factor is structurally related to the c-myb proto-oncogene and is
involved in the control of proliferation and/or differentiation of mature B lymphocytes. We
have shown previously by PCR analysis that A-myb is preferentially expressed in CD38+
CD39− sIgM− mature B cells. We demonstrate here, using in situ hybridization, that A-
mybexpression is restricted to the dark zone of human tonsils and lymph nodes.
Furthermore, we show that A-Myb expression is cell cycle regulated both in tonsillar B cells …
Abstract
The A-Myb transcription factor is structurally related to the c-myb proto-oncogene and is involved in the control of proliferation and/or differentiation of mature B lymphocytes. We have shown previously by PCR analysis that A-myb is preferentially expressed in CD38+ CD39− sIgM− mature B cells. We demonstrate here, using in situ hybridization, that A-mybexpression is restricted to the dark zone of human tonsils and lymph nodes. Furthermore, we show that A-Myb expression is cell cycle regulated both in tonsillar B cells and in Burkitt’s lymphoma cell lines, being detectable only in the S and G 2/M phases of the cell cycle and not in G 0/G 1 phase. Strong proliferation of resting human B cells induced in vitro by a variety of physiologic signals, including anti-μ, CD40 ligand, IL-2, IL-4, IL-6, IL-13, IFN-γ, TNF-α, anti-CD19, and anti-CD20, failed to induce A-myb expression, suggesting that proliferation alone is not sufficient for A-myb expression in the absence of induction of a true centroblast phenotype. Finally, we show that differentiation of germinal center B cells in vitro toward either memory or plasma cells is accompanied by rapid down-regulation of A-myb expression. We conclude that A-myb is a marker of centroblasts generated in vivo.
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