Lymphocytes that Bind IgE

spontaneous rosettes with sheep erythrocytes (E), 10.6% cells having surface immunoglobulin (SIg), and 15.5% binding IgG as shown by rosette formation with IgG-coated ox red cells (E0A). Fractionation of the lymphocytes into populations rich in spontaneously E-rosetting cells and cells with SIg indicated that the majority of the lymphocytes forming E0'-IgE rosettes belonged to the SIg-positive lymphocytes. Analyses of lymphocyte populations lacking cells forming EoA rosettes and of rosetting with mixed indicator cells both demonstrated that over 90% of the lymphocytes forming E0'-IgE rosettes did not form E0A rosettes and apparently had no Fc receptors for IgG. Pretreatment of the lymphocytes with trypsin in amounts that did not alter the number of EOA-rosetting cells abolished the E1'-IgE rosette formation. These data indicate that a subpopulation of normal human peripheral lymphocytes, probably belonging to the B-cell type, binds IgE presumably via trypsin-sensitive receptors specific for the Fc fragment of IgE. The This is publication no. 1205 from the Scripps Clinic and Research Foundation. Dr. Gonzalez-Molina is the recipient of an Intemational Fellowship from Eli Lilly and Company. Receivedfor publication 7 September 1976 and in revised form 13 December 1976. surface markers of these lymphocytes resemble those of cultured human lymphoblastoid cells that have recently been shown to bind IgE.