The formation and release of slow reacting substance of anaphylaxis (SRS-A) by rat and mouse peritoneal mononuclear cells induced by ionophore A23187.

The capacity of the calcium ionophore A 23187 to induce the formation of SRS-A was used in an attempt to identify the nature of the cells that are responsible for the formation of this material. In agreement with previous observations, rat and mouse peritoneal mast cells were found to contribute very little to the total amount of SRS-A that was made, and in fact their removal from the cell suspensions resulted in an augmentation of the amount of SRS-A that was found. Discontinuous Ficoll and bovine serum albumin gradients were employed to further characterize these SRS-A-releasing cells from induced peritoneal cells. SRS-A was produced by nonspecific esterase-positive and latex-phagocytizing mononuclear cells. By electron microscopy, these cells had macrophage-like characteristics. In contrast, rat alveolar macrophages and a macrophage-like cell line of mouse origin both failed to produce large amounts of SRS-A. The results suggest that SRS-A formation may be the property of an as yet imperfectly characterized subclass of macrophages.