Mast Cells and Control of Transendothelial Transport: the Role of Histamine

— The effect of human mast cells (MC) (HMC-1 line) on transendothelial transport (TET) of albumin and low-density lipoproteins (LDL) was studied using a two-chamber system with pores 1 μm in diameter. Human endothelial cells (EC) (line EA.hy926) were placed in the collagen-coated upper chamber and cultivated for 2–3 days until a visual monolayer was achieved. After that, 200 μg/mL LDL and 200 μg/mL albumin were added to the upper chamber. Intact MC or activated by aggregated human IgG or compound 48/80 were added to the lower chamber. Protein TET (a passage from the upper to the lower chamber through the EC monolayer) was assessed after 5 and 24 h. It turned out that the presence of MC (intact or activated) in the lower chambers retarded LDL and albumin TET after 24 h, but not after 5 h. LDL transport was found to be more sensitive to the inhibitory effect of MC than albumin transport. The suppressive effect of MC depended mainly on histamine and was canceled by histamine H1-receptor antagonist (but not of H2-receptor).