Effect of culture conditions on mast cell eicosanoid synthesis

When mast cells are grown in culture from mouse bone marrow cells, some cells are in suspension and some attach. The cells in suspension released leukotrienes and thromboxane when stimulated. Removal from the attached cells increased eicosanoid formation in the suspended cells two- to six-fold. The upregulation of arachidonic acid metabolism seemed to be due to an increase in phospholipase activity. The attached cells resembled macrophages in morphology, but stained positively for mast cells and produced PGD₂ an arachidonic acid metabolite which is characteristic for mast cells. The attached cells did not synthesize eicosanoids when stimulated with IgE/antigen or A23187. Addition of arachidonic acid caused cyclooxygenase product formation but not leukotrienes. No 5-lipoxygenase was detected by immunoblot analysis. Lack of eicosanoid synthesis was, therefore, due to the loss of 5-lipoxygenase and phospholipase activity, while the cyclooxygenase was preserved. These experiments demonstrate that attachment of mast cells to plastic can significantly alter their eicosanoid metabolism.