Immune discrimination between commensals and pathogenic bacteria.

Interaction with various bacteria is essential for the development of various components of the immune system. To prevent disease, the immune system must continuously discriminate between commensal and pathogenic bacteria. The immune system employs several mechanisms to discriminate between beneficial and harmful bacteria. This ensures selective immune tolerance toward commensals, especially in the gastrointestinal tract. Both commensal and pathogenic bacteria contain features that provoke immune responses. However, how the immune system reacts to or eliminates bacterial infections while preserving commensals is not fully understood. This review aims to explore the underlying mechanisms used by the immune system to distinguish between commensals and pathogenic bacteria. The review also addresses how commensals interact with immune system components to facilitate immune discrimination and host protection. Finally, dysbiosis and therapeutic interventions used to restore microbial balance are also discussed in this review.