Pre-incubation of RAW264.7 cells with combinations of MK-801 and ketamine did not affect the magnitude of inhibition of macrophage TNF secretion observed in the presence of ketamine (or MK-801) alone. Figure 4 depicts results for macrophages stimulated with vancomycin-or daptomycin-exposed MW2; responses to antibiotic-exposed LAC were similar (data not shown). One hour prior to stimulation, either ketamine at 100 μM, MK-801 at 150 μΜ, or both were added to the indicated wells. Cells were then incubated for 18 hours; supernatants were collected and analyzed for TNF content by ELISA. Lane 1 (control) represents the mean TNF production by macrophages not stimulated with bacteria. The mean includes wells exposed to ketamine, MK-801, both ketamine and MK-801, and neither. In the absence of bacteria, TNF secretion was minimal and was not affected by ketamine and/or MK-801. NMDA augments macrophage TNF secretion in response to antibiotic-treated CA-MRSA bacteria: both ketamine and a competitive NMDA receptor antagonist, APV, block this effect