Influence of anions, cations and osmolarity on IgE-mediated histamine release from human basophils

Allergen-activated human basophils require Ca2+ for the in vitro release of histamine. This study evaluated the importance of anions, cations and osmotic pressure on histamine release from human basophils. All media contained 1 mM Ca2+ and various salts or sugars were used to replace the NaCl-KCl of the control medium. Permeant anions supported release of histamine with the following order of activities: acetate - greater than Br-, I-, greater than Cl- greater than SO42-. When monovalent cations of the standard medium were replaced, RbCl, CsCl, KCl or NaCl gave results identical to the NaCl-KCl control medium; choline chloride usually enhanced while LiCl inhibited release. Finally, when sugar solutions were used to replace monovalent anions and cations of the standard medium: mannitol, lactose, sucrose, sorbitol, fructose and glucose each supported histamine release. Increasing the osmolarity of the medium by adding additional NaCl-KCl enhanced the ability of suboptimal concentrations of ragweed antigen E or anti-IgE to activate and to release histamine from leucocytes. The results indicate that histamine from leucocytes. The results indicate that histamine release from basophils requires only Ca2+ and do not support the "chemiosmotic swelling' hypothesis of secretion for these cells.