ANTI-IGE INDUCES THE OPENING OF NON SELECTIVE CATION CHANNELS ON HUMAN BASOPHILS

Basophils play a major role in allergic reactions - particularly in la te phase reactions - by releasing histamine and other mediators of inf lammation. Although transmembrane ion fluxes are thought to play an im portant role in the modulation of histamine release, little is known a bout ion pathways through the basophil membrane. We thus studied human basophils from normal subjects (n = 25 cells) with the patch-clamp me thod. We observed that IgE-dependent activation of human basophils led to the opening of non selective cation channels with a 20pS conductan ce. This was obtained when the patch pipette was applied onto the cell surface and sealed onto it in order to measure transmembrane currents on a small surface of intact basophils (cell-attached configuration). Non selective channels with the same 20pS conductance were also obser ved when a membrane patch was detached from basophil and its inner sid e placed in a Ca2+-containing medium (inside-out configuration). These data are a first contribution of the patch-clamp method in the unders tanding of ion movements in human basophils.