Legionella pneumophila Philadelphia-1 (Lp-1) can grow intracellularly in A/J mouse peritoneal macrophages (A/J Mφ).   We previously reported that 2-deoxy-D-glucose (2dG), when added in macrophage culture media, inhibited the intracellular multiplication of Lp-1 in A/J Mφ.   We found that 1mM of 2dG caused LC3-II-conversion that reflects an induction of autophagy and that 1 and 10mM of 2dG induced apoptosis associated with caspase-4 activation.   We therefore investigated whether 2dG-induced autophagy or apoptosis suppresses the replication of Lp-1 in 2dG-treated A/J Mφ.   When autophagy-related 5 (Atg5) was knocked down by RNA interference, the Atg5-siRNA-transfected cells revealed an enhanced replication of Lp-1 in A/J Mφ compared with the nontargetting siRNA-transfected cells.   However, caspase-4 inhibitor did not affect the 2dG-induced inhibition of intracellular multiplication of Lp-1 in A/J Mφ.   These findings suggested that autophagy, not apoptosis, suppressed the intracellular growth of Lp-1 in A/J Mφ  when 1 or 10 mM of 2dG were added to the culture media.