The effect of glutamine-mediated synchronization on complement susceptibility in breast cancer cell lines. All populations of cells were grown to confluency in separate culture flasks. Unsynchronized cells were maintained in 10% FBS DMEM supplemented with 2 mM L-glutamine, while some cells were subsequently maintained in glutamine deficient-media for 48 hours (Gln Deprived), and of this group, some were subsequently supplemented with 2 mM L-glutamine for 8 hours (Gln Restored). All populations of cells were sensitized with 20 μg of rabbit polyclonal antibody to β2-microglobulin and subjected to 25% fresh normal human serum (NHS). After 4.5 hours of incubation with NHS at 37°C, supernatants were collected and tested for LDH activity to determine percent lysis.