[Possible presence of protein kinase in human peripheral blood eosinophils]

Peripheral blood eosinophils from normal subjects and patients with atopic dermatitis were isolated on a Percoll gradient and incubated with [gamma 32P] ATP in the presence of Mg2+. After the reaction was stopped, SDS/PAGE was performed and autoradiography was used to determine the incorporation of 32P into the proteins in the eosinophils. Both normodense and hypodense eosinophils showed 32P incorporation into the proteins at the molecular weights of 65 kDa & 66.2 kDa. These reactions were dependent upon Mg2+ concentration, and maximal response was observed at concentrations of 2-6 mM MgCl2. 32P incorporation into the bands was dependent upon the reaction time and temperature, and maximal response was observed at 20 degrees C. 32P incorporation into the proteins was inhibited by Ca2+ in a dose-dependent manner. Cyclic GMP at concentrations of 5 x 10(-8) to 5 x 10(-6) M enhanced the 32P incorporation. These data suggest the possible presence of protein kinase in human peripheral blood eosinophils.