Atomic force microscopy to study the effects of ITIM-bearing Fc gamma RIIBon the activation of RBL-2H3 cells

We have studied here the effects of ITIM-bearing Fc gamma RIIB2 on the Fc e psilon RI-dependent activation of rat basophilic leukemia (RBL-2H3) cells b y atomic force microscopy (AFM). AFM images showed that ruffling and degran ulation of RBL-2H3 cells were significantly reduced but the cell spreading was not by the co-clustering of Fc gamma RIIB2 and Fc epsilon RI. From the results it was shown that the co-clustering of ITIM-bearing negative co-rec eptors in a single RBL cell hardly induce the degranulation though the [Ca2 +](i) increased transiently in the cell. This suggested that secretory resp onses and the membrane ruffling which were induced by the crosslinkng of Fc gamma RII should be negatively controlled by the co-clustering of Fc gamma RII. (C) 2000 Elsevier Science B.V. All rights reserved.