ULTRASTRUCTURE OF RESTING AND RH-GMCSF-TREATED HUMAN MACROPHAGES DERIVED FROM BLOOD MONOCYTES

The ultrastructure of cultured blood monocyte-derived human macrophage s was investigated and correlated under the effect of different doses of rh-GMCSF (dose 1=25 IU/ml, dose 2=125 IU/ml and dose 3=350 IU/ml). Resting macrophages showed irregular cell borders and pseudopodia push ed out in all directions. Their cytoplasm depicted rough endoplasmic r eticulum and Golgi complex in the perinuclear area. Lipid globules, pr imary lysosomes and mitochondria were characteristically prominent. rh -GMCSF-stimulated macrophages were more voluminous and their nuclei we re irregular in outline, with predominance of euochromatin over hetero chromatin. The cytoplasm was overcrowded by an increasing number of or ganelles including lysosomes, phagolysosomes and mitochondria. Golgi c omplex demonstrated a wide-spread distribution along the cells, with p rofound membrane expansion and cisternal dilatation; especially, in ce lls treated with dose 2. Electron dense osmiophilic deposits (collapse d membranes) were seen in association with lipid globules, which were commonly polarized at cell peripheries. Most of these changes were dos e dependent. However, cells treated with dose 3 manifested additionall y well-developed centrioles, inapparent nuclear membrane, display of m icrofilaments and well-established adhesions. The demonstrated ultrast ructural changes in rh-GMCSF-treated human macrophages indicated prono unced activation, which supports the reported clinical effect of this cytokine.