Phagocytosis of formol treated red blood cells

Formol treated red blood cells have been established to be phagocytized by human leukocytes in the presence of compatible AB0 standard test sera in case such red blood cells are stored continuously in water or in case they are incubated in saliva in advance for one hour at least at 37 degrees C. If formol treated red blood cells are continuously stored in 0.9% NaCl solution or if they are lyophilized in addition they will not be engulfed by human leukocytes in presence of compatible standard test sera of the AB0 system. The additional treatment with papain of formol treated red blood cells will cause a moderate phagocytosis.