Cytokine regulation of hFcRI expression in transgenic mice. (A) Bone marrow-derived neutrophils were cultured overnight with TNF- and/or GM-CSF and stained for surface expression of FcRI. Cells cultured in the presence of cytokines (bold lines) were compared with cells cultured in medium alone (thin lines). Gr-1-PE was used to identify granulocytes. (B) Effect of GM-CSF and TNF- on hFcRI expression on bone marrow-derived macrophages. Cells of nontransgenic (thin lines) and transgenic (bold lines) mice were cultured for 8 days. Cells were stained with anti-hFcRI MoAb A77-FITC and counterstained with F4/80-biotin/streptavidin-PE to define macrophages. This experiment was repeated four times with similar results.