IgE REGULATION BY T CELL DERIVED FACTORS

ConA and Histamine activated T cells and their crude sups were assayed for suppressive activity on IgE producing U-266 cell line.Detectable and comparable degree of suppression was obtained using either the co-culture or the supernatant protocols.Separation of the effector population into T4+ and T8+ subsets showed the most effective cells being in the T8+ fraction.Control experiments demonstrated that the IgE down regulation was select since no impairement of a non-immunoglobulin protein such as beta2 microglobulin occurred in the presence of T cell or T cell derived factors. In addition, a number of HTLV I transformed T cell lines were explored for capacity of producing factors able to suppress IgE synthesis in the U-266 cell line and 4 out of 25 cell lines tested could be shown to do this in a constitutive manner. Kinetic studies suggest the inhibition occurring at a transcriptional level. The data indicate the T cell-myeloma system as an interesting model to better define regulation of IgE in Humans.