ESTIMATION OF EFFECTIVE EOSINOPOIESIS AND BONE MARROW EOSINOPHIL RESERVE CAPACITY IN NORMAL MAN

The eosinophil reserve capacity of the post-mitotic granulocyte compartment in the bone marrow and the effective eosinopoiesis in three haematologically normal men have been quantified by means of kinetic parameters of ³H]thymidine flash-labelled peripheral blood eosinophils. From (a) the time of the appearance in the blood of labelled eosinophils after the tracer injection, (b) the inflow characteristics of the labelled eosinophils in the blood and (c) the magnitude of the eosinophil granulocyte pool in the venous blood, the effective eosinopoiesis (i.e. the eosinophil turnover) was calculated to range between 0.014 and 0.031 × 10⁹ cells/kg body weight per day (mean 0.22 × 10⁹ cell/kg per day). The post-mitotic eosinophil reserve capacity of the bone marrow ranged from 0.09 to 0.20 × 10⁹ cells/kg body weight (mean 0.14 × 10⁹ cells/kg). The large reserve pool and the high turnover rate may contribute to sudden rises of the peripheral blood oesinophil counts in some cases of eosinophilia.