EFFECT OF CULTURE CONDITIONS ON MAST-CELL EICOSANOID SYNTHESIS

When mast cells are grown in culture from mouse bone marrow cells, som e cells are in suspension and some attach. The cells in suspension rel eased leukotrienes and thromboxane when stimulated. Removal from the a ttached cells increased eicosanoid formation in the suspended cells tw o- to six-fold. The upregulation of arachidonic acid metabolism seemed to be due to an increase in phospholipase activity. The attached cell s resembled macrophages in morphology, but stained positively for mast cells and produced PGD2 An arachidonic acid metabolite which is chara cteristic for mast cells. The attached cells did not synthesize eicosa noids when stimulated with IgE/antigen or A23187. Addition of arachido nic acid caused cyclooxygenase product formation but not leukotrienes. No 5-lipoxygenase was detected by immunoblot analysis. Lack of eicosa noid synthesis was, therefore, due to the loss of 5-lipoxygenase and p hospholipase activity, while the cyclooxygenase was preserved. These e xperiments demonstrate that attachment of mast cells to plastic can si gnificantly alter their eicosanoid metabolism.