Colony‐stimulating factors and interferon‐gamma differentially affect cell surface molecules shared by monocytes and neutrophils
Monocytes and neutrophils share a common progenitor and perform many similar functions, as reflected in the expression of several shared membrane molecules. We show here that such molecules can be independently regulated by the cytokines interferon‐gamma (IFN‐γ) and the colony‐stimulating factors (CSF) in the context of the cell type on which they are present. Thus, IFN‐γ causes neutrophils to express the high‐affinity receptor for IgG, FcγRI, which has been considered to be a monocyte‐specific receptor. Although neutrophil FcγRI never reaches the levels present on monocytes. it is induced more rapidly and by lower amounts of IFN‐γ than monocyte FcγRI. Of the CSF, only macrophage (M) CSF has an effect which is to cause a decrease in expression of monocyte FcγRI. Secondly, after culture monocytes express FcγRIII which is constitutively expressed by neutrophils. Although ncutrophil FcγRIII can be readily modulated by IFN‐γ. granulocyte (G) CSF and granulocyte macrophage (GM) CSF, these cytokines do not alter the low levels of monocyte FcγRIII. Thirdly, expression of the gp55 protein recognized by CD14 monoclonal antibodies is decreased after exposure of monocytes to IFN‐γ. Neutrophils express low levels of CD14 and, in this case. IFN‐γ causes an increase in the CD 14 antigen on these cells. Of all the molecules investigated, only HLA class II is confined to monocytes. with increases in expression induced by IFN‐γ but not by the CSF.