International Journal of Cell Cloning, Vol 4, 167-185, Copyright © 1986 by AlphaMed Press
Parameters affecting the in vitro maturation of human monocytes to macrophages
H Maoz, A Polliack, V Barak, S Yatziv, S Biran, H Giloh and AJ Treves
In vitro maturation of human monocytes to macrophages was characterized by
morphological criteria, cell size and lysosomal enzymes activity. Purified
populations of monocytes were maintained in culture at either adherent or
nonadherent conditions and their maturation to macrophages was observed in
both cases. The addition of external factors such as hydrocortisone and
vitamin D3 inhibited monocyte maturation. In the absence of external
factors, nonadherent monocytes were inhibited in their maturation for up to
10 days when plated at crowded cell concentrations. In addition, the
presence of human serum in the culture media had a higher inhibitory
activity than similar concentrations of fetal calf serum. Supernates from
crowded macrophages were also inhibitory for monocyte maturation. We
suggest the possibility that cell crowding, as well as soluble factors
found in the serum and probably secreted by macrophages, participate in the
regulation of monocyte development by inhibiting their maturation. Once
released from this inhibitory signal or environment, the monocytes mature
to macrophages.
