Studies on the Role of Calcium in the Anaphylactic Histamine Release from Isolated Rat Mast Cells

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Abstract
The anaphylactic histamine release from isolated, sensitized rat mast cells was studied. Before incubation the mast cells were kept concentrated (106 cells/ml) in either calcium‐free buffer (these cells are denoted Mc) or buffer containing 1 mM‐CaCl2 (denoted McCa). The cells were diluted 100 to 400 times when exposed to antigen. The histamine release from Mc and McCa exposed to antigen plus CaCl, was identical, but significantly lower than observed for McCa incubated with antigen alone. EDTA (1 mM) abolished the effect of CaCl2 in the incubation medium. Pre‐incubation of McCa in the absence of calcium decreased the response to antigen, and optimal reduction of histamine release was observed within one minute at 37° and five minutes at 21°. The time courses for the anaphylactic histamine release in the presence of calcium from Mc and McCa were identical at both 21° and 37°. The release from McCa in the absence of calcium was considerably faster at both temperatures.