Increased IgE-dependent cytotoxicity by blood mononuclear cells of allergic patients

Peripheral blood mononuclear cells from 14 healthy donors and 22 allergic patients were incubated with 51Cr-labelled chicken erythrocytes coated with an IgE myeloma protein or rabbit IgG antibodies. Mononuclear cells from patients with severe atopic disorders released a significantly greater percentage of 51Cr (P less than 0.001) from IgE-coated target cells than mononuclear cells from healthy controls, patients with mild atopic disease, or patients with severe atopic disease taking oral prednisone. Specific 51Cr-release from IgE-coated target cells was directly correlated to the percentage of monocytes (latex-ingesting cells) with Fc receptors for IgE (r = 0.87, P less than 0.01) as detected by a rosette assay employing ox erythrocytes coated with IgE. Mononuclear cells from patients and normals released similar amounts of 51Cr from IgG-sensitized target cells. Depletion of monocytes from mononuclear cell preparations from two severe atopic patients decreased 51Cr-release from IgE-coated target cells to levels seen in healthy donors or patients with mild allergic disease. These results demonstrate that mononuclear cells from severely allergic patients have a significantly increased cytotoxicity toward IgE-coated targets coated target cells and that this cytotoxicity correlates highly with the percentage of monocytes with Fc receptors for IgE in these mononuclear preparations.