PDCD1 and bacterial infectious disease: Increased susceptibility to bacterial infections in SAH is due to endotoxin induced neutrophil suppression7 and high expression of inhibitory receptors on lymphocytes, particularly programmed cell death 1 (PD1), T-cell immunoglobulin and mucin domain–containing protein 3 (TIM3) and their ligands PD ligand 1 (PDL-1) and galectin-9, respectively8.