The Fc OxyBURST™ Green assay reagent comprises bovine serum albumin (BSA) that has been covalently linked to dichlorodihydrofluorescein (H₂DCF) and then complexed with a purified rabbit polyclonal anti-BSA antibody. When this immune complex binds to Fc receptors, the nonfluorescent H₂DCF molecules are internalized within the phagovacuoloe and subsequently oxidized to green-fluorescent 2''7'-dichlorofluorescein.