Study of granulocytopoiesis in drug-induced agranulocytosis using 3HTdR autoradiography.

Abstract

Autoradiographic study of granulocytopoiesis was carried out in 6 patients with acute drug‐induced agranulocytosis (5 induced by pyrazolone derivatives, and one by gold salt) by in vitro bone marrow labelling with 3HTdR. During the days preceding the normalisation of blood granulocyte count, 11 bone marrow samples were analysed when the marrow was promyelocytic‐myelocytic (or myeloblastic‐promyelocytic). The finding of an increased number of cells synthesizing DNA can be explained by the increase of the growth fraction of myelocytes close to one. Calculation of proliferation parameters on the basis of: DNA synthesis time equalling 12 h (Stryckmans et a1 1966) demonstrates an increased birth rate of cells in the proliferative compartment of granulocytopoiesis and, consequently, an increased outflow into the maturation compartment at the rate 2.2‐2.7 times the original amount. A higher mitotic index in the same bone marrow samples gives proof of an increased mitotic activity. The results presented confirm the findings from cytological analysis, i. e. that promyelocytic‐myelocytic (and also myeloblastic‐promyelocytic) marrow (a morphologic pattern erroneously termed ‘maturation arrest’) reflects a proliferative push in the regenerative phase of granulocytopoiesis in acute agranulocytosis.