6.8—Non-specific responses to infection

Non-specific responses act against many pathogens and begin rapidly. Histamine-driven inflammation changes blood flow and capillary permeability; interferons limit viral replication; phagocytes engulf and digest foreign material.

During phagocytosis, a phagocyte recognises non-self antigens, encloses the pathogen in a vacuole, lysosomes fuse with it and digestive enzymes break it down. Antigen presentation can then initiate a specific response.

A splinter can trigger local swelling as histamine recruits fluid and phagocytes. A virus-infected cell can release interferons that warn nearby cells and activate immune defences.

Non-specific does not mean unregulated or ineffective, and it is not the same as antibody specificity. Keep inflammation, interferon action and phagocytosis as distinct mechanisms.