IMMUNOCYTOCHEMICAL STUDY OF UPTAKE OF EXOGENOUS CARRIER-FREE COPPER-ZINC SUPEROXIDE-DISMUTASE BY PERIPHERAL-BLOOD LYMPHOCYTES

We recently demonstrated that exogenous copper-zinc superoxide dismuta se (SOD) reduced HIV replication in tumor necrosis factor alpha activa ted chronically HIV-infected promonocytic U1 cell line and in peripher al blood mononuclear cells coculture. However, whether exogenous SOD p enetrates the cellular membrane or acts extracellularly has been remai ned controversial. SOD has been considered as not to penetrate the cel lular membrane because of its high molecular weight, thus the main sit e of action is presumed to be extracellular. In order to determine whe ther exogenous SOD penetrates inside the cell, we utilized a gentle im munocytochemical method to detect Mn and Cu,Zn SOD in peripheral blood lymphocytes incubated with various concentrations of exogenous carrie r-free Cu,Zn SOD without prior permeabilisation of cell membranes. Aft er 24 hrs. the total SOD activity and immunocytochemical studies were performed. Here we demonstrate clearly that a large amount of carrier- free Cu,Zn SOD, added exogenously, penetrates the cellular membrane an d increases total SOD activity.