PTPN22 and bacterial infectious disease: Increased intracellular expression of LYP in patients with mycobacterial infection (46, 47), the involvement of PTPN22 in downregulation of T-cell function (30), and the participation of PTPN22 in invasive bacterial infection (16) have been considered as evidence to conclude that PTPN22-C1858T polymorphism increases the risk of mycobacterial disease onset (17).