Formation and Binding of Histamine by Free Mast Cells of Rat Peritoneal Fluid

Abstract

Suspensions of the cells of rat peritoneal fluid have a marked ability to decarboxylate C14 l-histidine and bind the resulting histamine in stable form. The evidence is strong that this activity is due almost entirely to mast cells; these constitute about 4% of the total number of cells present. The effects of temperature, time, and ph on this process were found to be characteristic of enzymic reactions. Preincubation of cell suspensions with nonisotopic histamine had no effect on the formation and binding of C14 histamine; this is evidence that exogenous histamine cannot enter the bound condition in free mast cells. The effects of histidine analogs on binding is described. Disruption of the mast cells results in a considerable loss in histamine forming activity. However, a fairly stable, soluble histidine decarboxylase can be obtained from the disrupted cells. A new method for determination of histamine as the S35 dibenzenesulfonyl derivative is described.