Similarity in the Mechanism of Histamine Release Induced by Cationic Protein from Neutrophils and by Complement Dependent Ag-Ab Reaction

Abstract

It has been shown previously that band 2 protein obtained from the lysosomes of rabbit neutrophils induces specific histamine release from rat peritoneal mast cells [10]. The activation of esterase was shown to be an initial step followed by active state I. This state decays without rendering the cells unresponsive to rechallenge. The establishment of unresponsiveness to band 2 protein in the presence of DNP was attributed to the decay of a second active state. In the present investigations, an attempt has been made to determine whether the same pathway is activated by complement-dependent antigen-antibody reaction. It has been found that the cells made unresponsive to band 2 protein in the presence of DNP also became unresponsive to Ag-Ab-C. Similarly, the cells made unresponsive to Ag-Ab-C by reacting them in the presence of DNP or at 15 °C became unresponsive to band 2 protein. Unlike Ag-Ab-C, band 2 protein itself released histamine at 15 °C. Band 2 protein, but not Ag-Ab-C, activated the cells at 10 °C, so as to release histamine after removal of the stimulus prior to the resus-pension of these cells in Tyrode at 37 °C. The rates of activation of mast cells by these two stimuli differ markedly. These findings are discussed in view of the proposed mechanism of histamine release.