The mobilization of hematopoietic progenitors to peripheral blood is predictive of the hematopoietic syndrome after total or partial body irradiation of mice.

In previous studies we showed that administration of mobilizing growth factors (MGFs) to mice previously exposed to total body irradiation mobilizes to peripheral blood (PB) a number of progenitors that correlates with the total reserve of progenitors surviving the exposure. Now we have tested whether this finding is independent of the radiosensitivity of the mice and of the homogeneity of the radiation exposure. Also we have investigated whether numbers of mobilized progenitors predict the hematopoietic syndrome after irradiation. Mice were subjected to partial or total body irradiation and treated with MGFs. Thereafter, the number of colony-forming units granulocyte-macrophage progenitors in PB was correlated with the total reserve of surviving progenitors and with the nadir of leukocytes after the irradiation. The number of progenitors mobilized to PB after irradiation of normal and radiosensitive mice showed the same correlation with respect to the reserve of bone marrow progenitors surviving the exposure. Additionally, the number of mobilized progenitors correlated with the leukocytes' nadir after the irradiation, regardless of homogeneous or inhomogeneous exposures. In a mouse experimental model, the number of hematopoietic progenitors mobilized to PB by MGFs is a good predictor of the hematopoietic syndrome occurring after total or partial body irradiation.