Monocytes from both atopic donors and healthy individuals express Fc epsilon RI, but the previously reported different expression levels between the two groups seem to be directly related to the absence or presence of IgE in the serum. This may be due to the fact that Fc epsilon RI is subjected to a constant turnover process which is slowed down but not prevented by ligand binding. In addition, free Fc epsilon RI on non-atopic monocytes are under control of a neuramindase sensitive structure(s), which influences signal transduction and IgE binding.