PROTHYMOSIN ALPHA-1 ANTAGONIZES THE INHIBITORY EFFECTS OF TRANSFORMING GROWTH-FACTOR-BETA-1 ON THE ADHESION OF PERIPHERAL-BLOOD LYMPHOCYTESTO HUMAN UMBILICAL VEIN ENDOTHELIAL-CELLS

We investigated the in vitro effects of both prothymosin alpha 1 (Pro alpha 1) and transforming growth factor-beta 1 (TGF-beta 1) on the adh esion of peripheral blood lymphocytes (PBL) and on the expression of t he adhesion molecules, endothelial-leukocyte adhesion molecule-1 (ELAM -1), intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhe sion molecule-1 (VCAM-1) on human umbilical vein endothelial cells (HU VECs). TGF-beta 1 moderately but significantly decreased PBL-binding t o interleukin-1 (IL-1)-stimulated HUVECs. However, Pro alpha 1 in comb ination with TGF-beta 1 completely restored the TGF-beta 1 mediated ef fects. Other thymic peptides tested were ineffective. On HUVECs, TGF-b eta 1 diminished ICAM-1 and VCAM-1 expression, leaving ELAM-1 unchange d. Pro alpha 1 in combination with TGF-beta 1 showed no significant ef fects on ELAM-1 expression, but antagonized the TGF-beta 1-induced dec rease of ICAM-1 and VCAM-1 expression on activated HUVECs.