GOLD BINDING-SITES IN RED-BLOOD-CELLS

Gold distribution and binding sites in blood and red blood cells (RBCs) have been determined. RBCs were separated from plasma and lysed. The cytosol was separated from membranes which were then solubilized via detergents. Total gold in each fraction was measured via flow injection analysis (FIA) with inductively coupled plasma mass spectroscopy (ICP-MS) detection. Various high-performance liquid chromatography (HPLC) techniques such as ion-pairing, reversed-phase and size-exclusion chromatography have been applied to RBC samples prepared by incubation with specific compounds and to RBCs from rheumatoid arthritis (RA) patients. Preliminary studies of RA patients' samples indicate very different gold uptake into RBCs depending on the particular patient. Size-exclusion chromatography indicates that gold in the lysate is not bound principally to hemoglobin but rather to a significantly higher molecular weight species (about 330 000 Da). Low molecular weight species in the ultrafiltered RBC lysate include the dicyanogold(I) anion and possibly the bis(glutathione)gold(I) complex. Incubation experiments have been designed to measure dicyanogold(I) and gold drug uptake by RBCs. Experiments with 4,4'-diisothiocyanatostilbene-2,2'-D,L-sulfonic acid (DIDS), an anion channel blocker, indicate that dicyanogold(I) enters the cell by some path other than the anion channel. The inhibition of gold uptake on addition of free cyanide suggests that the loss of cyanide from dicyanogold(I) is important in dicyanogold(I) uptake by RBCs. Given the rapid uptake of dicyanogold(I) and its apparently high tolerance in humans, this material is suggested as a possible therapy in the treatment of AIDS.