suspension plates so that the population of dying cells can be
transferred easily to the well containing attached macrophages.
In L929sAhFas cells, apoptosis is induced by agonistic anti-Fas antibody
(250 ng/ml, for at least 1 h) and necrosis by mTNF (10,000 IU/
ml, for at least 7 h). The choice of time points depends on the kinetics
of cell death and has to be optimized for each cell line and death
inducer. Macrophages are coincubated with target cells in a 1:1
ratio for at least 1 h. After that, cocultures of macrophages and target
cells are fixed overnight at 4 C in the 6-well plate by immersion
in TEM fixation buffer (2% glutaraldehyde containing 1 mM
CaCl2 and 0.1 M sucrose buffered with 0.1 M Na-cacodylate, pH
7.4). Following several rinses in 100 mM Na-cacodylate containing
7.5% w/v sucrose, the samples are post-fixed overnight at 4 C in 1%
w/v OsO4 in the same buffer (without sucrose).