Morphological aspects of glucocorticoid-induced cell death in human lymphoblastoid cells.

Morphological aspects of cell death associated with a cytolethal concentration of methylprednisolone sodium succinate (500 micrograms/ml) on the BLA1 lymphoblastoid cell line were studied over a 48-hr incubation period by light, transmission and scanning electron microscopy. Studies revealed two distinctive morphological changes induced by the steroid from 1 hr onwards after treatment. One showed contortion and "blebbing" of the cytoplasm and nucleus accompanied or followed by nuclear pyknosis, resulting in the formation of membrane-bounded bodies containing apparently normal cytoplasmic organelles with or without nuclear fragments. The other showed "rounding up" of the cell with loss of cytoplasmic protrusions and long slender surface processes, aggregation of well-preserved cytoplasmic organelles, accompanied by nuclear pyknosis and fragmentation. In both cases many of the features are typical of apoptosis. The subsequent degeneration of cells and fragments not unexpectedly resembled in vitro autolysis. This in-vitro system is suitable for studying the early biochemical events and intracellular control mechanisms of apoptosis.