Increased expression of adhesive proteins on leukocytes by TNF alpha.

To further elucidate the role of tumor necrosis factor alpha (TNF alpha) in cell adhesion, we investigated the effect of TNF alpha on the expression of surface adhesive protein. After treatment with TNF alpha for 1 h, the increased expression of surface adhesive proteins (beta subunit) was observed on granulocytes but not on monocytes or lymphocytes. The expression of Mac-1 (3,4-fold increase) was consistently enhanced more than p 150,95 (1.4-fold increase) and LFA-1 expression was unchanged. Dose-response and time course studies indicated a parallel relationship between TNF alpha-increased expression of surface adhesive proteins and TNF alpha-induced granulocyte adhesion. The anti-inflammatory drug Dexamethasone suppressed both TNF alpha-induced granulocyte adhesion and TNF alpha-induced expression of surface adhesive proteins. The inhibition of granulocyte adhesion correlated with the reduction of surface adhesive protein expression. The data suggest that one contributing factor in the mechanism by which Dexamethasone inhibited TNF alpha-induced granulocyte adhesion may be diminished expression of surface adhesive proteins.