The development of human megakaryocytes. II. CD4 expression occurs during haemopoietic differentiation and is an early step in megakaryocyte maturation.
CD4 expression is not limited to T cells and monocytes. In both mouse and man the antigen has been detected on some early haemopoietic progenitors and we have shown that some mature megakaryocytes (MK) express CD4, the surface molecule that serves as the high-affinity receptor for human immunodeficiency virus type-1 (HIV-1). Using a serum-free culture system in which sorted CD34+ haemopoietic progenitors are cultured with thrombopoietin (TPO), IL-3, IL-6 and SCF, we now show that CD4 expression is induced in virtually all developing haemopoietic cells. This phenomenon was particularly striking in the MK lineage, where CD4 expression began whilst the cells were still CD34+ but after they expressed CD41 (GPIIb/IIIa). CD4 expression and endomitotic polyploidization occur at the same time in MK development. In culture, maximum CD4 expression occurred 4-6 d after CD41 expression and lasted for a few days. Expression of CD4 declined gradually thereafter and most MK were CD4- by the end of the culture period. The amount of CD4 on the surface of some MK, as measured by intensity of fluorescence staining, exceeded that of normal monocytes and approached the brightness of T cells. Appearance of the surface antigen correlated with the presence of mRNA for CD4, as measured by RT-PCR.
Basch
R S
RS
Department of Pathology, New York University Medical Center, New York 10016, USA.
Dolzhanskiy
A
A
Zhang
X M
XM
Karpatkin
S
S
D018952:Antigens, CD34 / Q000378:metabolism; D001483:Base Sequence; D015704:CD4 Antigens / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008297:Male; D008533:Megakaryocytes / Q000166:cytology / Q000378:metabolism*; D008875:Middle Aged; D008969:Molecular Sequence Data; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism
D018952:Antigens, CD34; D015704:CD4 Antigens; D019039:Platelet Glycoprotein GPIIb-IIIa Complex