Detection of intracellular FV in quiescent platelets.

Control platelets were formalin-fixed and permeabilized with saponin as described in “Materials and methods.” Three different biotinylated, anti-FV monoclonal antibodies were then used to stain intracellular FV. Panel A is anti-HFV-237 that recognizes the FVa light chain; Panel B represents anti-HFV-227 that detects the FV connecting region (B domain); and Panel C is anti-HFV-271 that recognizes the heavy chain of FVa. The line histograms represent nonspecific antibody, and the shaded histograms represent the anti-FV monoclonals. All platelets bind the 3 monoclonals indicating that all platelets contain the entire FV molecule.