Eosinophil cationic protein (ECP) in the cerebrospinal fluid.

ECP (eosinophil cationic protein) has been measured by means of a specific radioimmunoassay in the cerebrospinal fluid (CSF) from 210 individuals with various diseases affecting the central nervous system. In the same specimens lactoferrin and albumin were measured as well, as indicators of neutrophil-involved inflammation and damage to the blood-brain barrier. From a patient reference group (n = 39) the upper "normal" limit for ECP was estimated to 1.7 microgram/l. In patients with acute cerebrovascular disease (n = 108) ECP levels were elevated in 38% of the cases which was a significantly (P less than 0.001) greater proportion than seen for lactoferrin (7%). In patients with acute infections of the CNS (n = 30) 67% had raised ECP levels with significantly higher levels (P less than 0.001) in those having bacterial infections. The ECP levels were significantly correlated (P less than 0.001) to the lactoferrin-levels in the whole infectious group. In patients with tumours (n = 25) raised levels of ECP were found in 67% of those with malignant and in 6% of those having benign tumours. This difference was statistically significant (P = 0.001). The ECP levels were closely related to those of lactoferrin (P less than 0.001) and albumin (P less than 0.005). Of the patients with multiple sclerosis (n = 19) 25% had raised ECP levels. This proportion was not significantly different from those having raised lactoferrin levels. In three patients extremely high ECP levels (70-455 micrograms/l) were found and a causal relationship between ECP and the brain tissue damage in these patients is suggested. In comparison with the neutrophil-related data the findings suggest a preferential involvement of eosinophils in some diseases affecting the central nervous system.