Increased acidophilia of eosinophil granules after EDTA treatment

The acidophilic reaction of eosinophil leucocyte granules from human, pig and horse blood smears was investigated by using May-Grünwald-Giemsa staining after previous treatment with EDTA and sodium citrate solutions. The same peak at 530 nm, but absorption values considerably higher than those of controls, were found in eosinophil granules after application of chelating agents, indicating that removal of metal cations could unmask basic groups in these structures.