The relationship between serum IgE and surface levels of Fc epsilon R on human leukocytes in various diseases: Correlation of expression with Fc epsilon RI on basophils but not on monocytes or eosinophils

Background: Expression of receptors for IgE (Fc epsilon R) have been mainly studied on mast cells and blood basophils in the context of allergic disea se, Some reports have noted limited expression of Fc epsilon R on other leu kocytes, including blood monocytes and eosinophils in certain patients. An association between human blood basophil expression of Fc epsilon RI alpha and serum IgE has been noted among allergic subjects. Objective: Recent evidence supports regulation of Fc epsilon RI alpha by fr ee IgE on both mast cells and basophils. We hypothesized that this relation ship would exist across an extremely wide range of IgE levels for human bas ophils, irrespective of underlying disease. We further examined whether a s imilar relationship existed between serum IgE and Fc epsilon RI alpha or Fc epsilon RII (CD23) expression on monocytes and eosinophils in these same s ubjects. Methods: Blood was obtained from nonallergic subjects (n = 3) and subjects with allergic asthma (n = 5), atopic dermatitis (n = 3), hypereosinophilic syndromes (n = 7), hyper-IgE syndrome (n = 6), helminth infestation (n = 6) , or IgE myeloma (n = 1). Levels of serum IgE were determined by using RIA and ranged from 3 to 4.7 mg/mL. Levels of cell surface Fc epsilon RI alpha, Fc epsilon RII, and IgE were measured by using immunofluorescence and now cytometry. Results: Basophil surface IgE density and Fc epsilon RI alpha expression co rrelated with serum IgE levels (r = 0.67 and r = 0.46, respectively; P < .0 1; n = 31) regardless of the disease state. In contrast, monocyte Fc epsilo n RI alpha expression did not correlate with serum IgE (r = 0.09, P > .5, n = 29), and low-level eosinophil Fc epsilon RI alpha expression was only de tected in a single asthmatic subject. CD23 expression was not detected on b asophils or eosinophils, except for the eosinophils from the donor with IgE myeloma, CD23 was present on monocytes from some donors but did not correl ate with serum IgE levels. Conclusions: In a variety of disease states, Fc epsilon RI alpha expression by basophils, but not monocytes or eosinophils, correlated with serum IgE levels across a 6-log range of IgE. These data support the concept of in vi vo regulation of Fc epsilon RI alpha on basophils by serum IgE and further demonstrate that this is independent of allergic disease per se.