Extracellular deposit of the cationic proteins ECP and EPX in tissue infiltrations of eosinophils related to tissue damage.

In a series of eosinophil inflammatory states affecting various organs (heart, gut, bladder and skin) we performed an immunohistochemical study of the eosinophil cationic proteins ECP and EPX. A strong correlation was noted between the liberation of ECP and EPX and tissue necrosis in all organs. In most cases ECP and EPX were found on the same location. However, one case indicated a possible differential release. Extracellular ECP and EPX were revealed concurrently with the two polyclonal antibodies and the monoclonal EG2 antibody. The latter binds to both ECP and EPX, but only during secretion. Since EG2 does not differentiate between ECP and EPX, but only during secretion. Since EG2 does not differentiate between EXP and EPX, it is for the first time demonstrated that both cationic proteins are correlated to tissue damage. The chymotrypsin-like cationic protein (CCP), related to neutrophils, showed a low correlation with the eosinophil cationic proteins in cases of tissue damage. The hypothesis is put forward that the release of eosinophil granule proteins and especially ECP results in a non-specific tissue damage.