Uptake of labeled CFH by normal washed platelets. Triple-washed platelets were incubated with or without CFH conjugated with Alexa Fluor 488 dye (A488-CFH, green color), then fixed, immunostained for platelet myosin IIA (myosin), and examined via laser fluorescence confocal microscopy. Midcell Z-slices of typical resting cells (flat, round shape with myosin staining in red) are shown in horizontal (left) and vertical (right) orientation. Platelets shown were incubated: (A) for 120 minutes in buffer; (B) with A488-CFH for 30 minutes; (C) with A488-CFH for 120 minutes. After 30 minutes, most of the platelet-associated A488-CFH was on the cell surface as indicated by peripheral staining; after 120 minutes, a substantial amount was observed inside platelets.