Cytochemistry and ultrastructure of pathologic granulation in myelogenous leukemia

The production of characteristic granules is one of the most specialized functions concerned with the development of granulocytes and monocytes. Leukemia-associated defects in the production of these highly specialized cell organelles reflect the perturbation of the RNA metabolism within the leukemic cells. Pathologic granulation can be of some clinical importance as a diagnostic aid in identifying various cytological types of acute leukemia as well as giving an indication for the profound perturbation in the intrinsic leukocyte regulation, as it occurs in preleukemic states or following treatment with some cytotoxic agents. The defects in granule production may lead either to a partial or complete reduction of a single or of several granular enzymes as well as in the partial or complete failure of the production of a given type of granules. On the other hand unusual increases of specific enzyme activities can be found as well as combination of characteristic granules of different cell types within one homogenous leukemic cell population. Ultrastructural evidence has been obtained that the production of granules may be disturbed at any morphologically identifiable stage of granulogenesis. Pathological agglomeration or fusion of granules with atypical cytosomes may lead to further abnormal subcellular structures exhibiting granular enzyme activities.