Eosinophil kinetics in the hypereosinophilic syndrome.

The kinetics of 51-chromium-labeled eosinophils were studied in 6 patients with the idiopathic hypereosinophilic syndrome. The kinetics of these cells were compared with 51-chromium-labeled neutrophils of 9 normal subjects. The patient studies consistently showed that autologous labeled eosinophils transiently left the circulating cell pool in the first 3 hours after infusion, re-entered the circulating pool, and then disappeared from the circulation with a mean blood half-life of 44 +/- 2.0 hours. In contrast, the neutrophils of normal subjects left the circulation progressively with an estimated blood half-life of 12.4 +/- 2.0 hours. These data suggest that the leukocytosis of the hypereosinophilic syndrome may be due to the presence in the blood of an increased number of cells with a relatively long blood half-life.