Induction of the expression of gag protein in HTLV-I infected lymphocytes by anti-ICAM 1 antibody in vitro.

Intercellular adhesion molecule 1 (ICAM 1) is an inducible protein ligand which is up-regulated during inflammation and is either not constitutively expressed or is only expressed at low levels. The expression of ICAM 1 increases in HTLV-I infected T cell lines as well as in CD4+ T-cells of peripheral blood lymphocytes (PBLs) from HAM/TSP patients. After PBLs of HAM/TSP patients were cultured in the presence of stimulating anti-ICAM 1 antibody, the expression of the HTLV-I gag protein in PBLs was observed by both immuno-histostaining and western blot analysis using HTLV-I Ag-specific mouse monoclonal antibody. These data thus suggested that the signal transduction via adhesion molecule, ICAM 1 could induce the transcription of the HTLV-I gene and this might therefore play an important role in the pathogenesis of HAM/TSP.