MAST-CELL-MEDIATED INDUCTION OF ICAM-1, VCAM-1 AND E-SELECTIN IN ENDOTHELIAL-CELLS IN-VITRO - CONSTITUTIVE RELEASE OF INDUCING MEDIATORS BUT NO EFFECT OF DEGRANULATION

Mast cell (MC)-mediated induction of intercellular adhesion molecule-l (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and of E-sele ctin was studied in cultures of rat heart endothelial cells (EC) and h uman umbilical vein EC (HUVEC) respectively. MC induced VCAM-1 and E-s electin, but hardly any ICAM-1 in EC. Induction was not dependent on M C degranulation, but seemed to be provoked by constitutively released substances, other than histamine, from MC. Coincubation of MC and EC, allowing for direct contact between the two cell types, was more poten t in induction than MC co-incubated separately from EC using a permeab le membrane. MC were less potent in induction than exogenous added cyt okines or LPS. Induction of cell adhesion molecules in rat heart EC wa s MC-specific, since EC incubations with either rat cardiomyocytes or heart fibroblasts had no effect. The data show that rat MC, independen t of degranulation, secrete mediators relevant for the induction of a specific set of EC adhesion molecules in vitro. This suggests a (suppo rtive) role for MC in cell-adhesion molecule induction in the endothel ium in settings of early or mild inflammation. The results are discuss ed in the context of inflammatory processes in the heart in vivo.