Relationship between total number and CMA-676–bound CD33 sites on peripheral blood cells in a characteristic patient over time. The solid line represents the number of CD33 sites available for binding to CMA-676 as estimated by the maximal fluorescence intensity obtained by incubating an aliquot of cells in vitro with excess CMA-676. The dashed line represents the fluorescence intensity of bound CMA-676 to cell surfaces. Near-complete saturation is seen 30 minutes after the start of the infusion.