We evaluated chemotactic properties of four sublines of rat basophilic leukemia cells using blindwell Boyden chamber assays. After sensitization with a mouse monoclonal IgE directed against dinitrophenyl (DNP), cells from sublines 2H3-C and 926a underwent chemotaxis toward DNP-bovine serum albumin (BSA) and sublines RBL-1 and 4A did not. Chemotactic responses required specific IgE and were determined by the IgE antigen specificity used for sensitization. The threshold for chemotaxis was on the order of 10(-10) M DNP-BSA. Release of incorporated [3H]-serotonin did not always parallel chemotactic responses, which suggests that chemotaxis and secretion may be two unlinked processes that occur during basophil activation. Our results predict a possible in vivo mechanism whereby specific chemotactic responses of basophils and other FcR epsilon-bearing cells are mediated via specific IgE bound to membrane FcR epsilon.

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