Immunocytochemical localization of albumin and factor XIII in thin cryo sections of human blood platelets.

Albumin and factor XIII alpha 2 were localized in human blood platelets by immunofluorescence and protein A-colloidal gold immuno-electron microscopy using thin and ultrathin cryosections of mildly fixed human blood platelets. Albumin was found in alpha-granules, co-distributing with beta-thromboglobulin in double label experiments. In platelets directly fixed in plasma, without previous washing, albumin was also localized on the plasma membrane and in the surface connecting system. Factor XIII alpha 2 was localized diffusely through the entire cytoplasmic matrix.