The Immunoglobulin E- and Calcium-Dependent Release of Histamine and Eicosanoids from Human Dispersed Mastocytosis Spleen Cells

Abstract

The clinical features of systemic mastocytosis have been ascribed to mast cell-dependent mediators, but there have been no studies of their release from isolated cells. We have investigated the release of histamine and eicosanoids from isolated spleen cells obtained from tissue of a mastocytosis patient undergoing therapeutic splenectomy. Dispersed cell preparations contained lymphocytes 65.9%, monocytes/macrophages 22.3%, neutrophils 9.9%, mast cells 1.1%, and eosinophils 0.8%; upon challenge with 0.1-3.0 microM A23187 they released histamine much greater than PGD2 greater than TXB2 greater than LTB4 greater than LTC4 approximately equal to LTD4 greater than LTE4. With immunological activation of passively sensitized cells, histamine and PGD2 release had similar dose-response characteristics, but TXB2, LTC4, LTD4, and LTE4 release differed in reaching maximum at 50 micrograms/ml and declining at 125 micrograms/ml anti-human IgE. Percoll centrifugation separated most of the histamine-containing cells to the middle of the gradient, but they were refractory to release with 0.3 microM A23187 or 50 micrograms/ml anti-IgE. Spontaneous release of histamine from these cells was not abnormally high (1.3%-4.5%). Electron microscopy of tissue sections revealed large numbers of mast cells with empty granules. It is possible that the refractory cells observed are such mast cells where intracellular histamine is no longer granule-associated. Most net histamine and PGD2 release was confined to cells at the bottom of the gradients (1.078-1.09 g/ml), although some release of PGD2 occurred near the top (1.05-1.058 g/ml). There was a significant correlation between the net release of histamine and PGD2 with both immunological (r = 0.92; n = 16) and A23187 (r = 0.97, n = 14) activation. These studies provide evidence for a link between PGD2 and histamine release in mastocytosis spleen cells.