Immune Defence

#Defence involves barriers, cells and communication

NIAID describes immune defence as a network of cells that circulate or live in tissues, recognise problems and communicate with one another. Skin contributes to the first line of defence; lymph nodes provide places where immune cells encounter information from other parts of the body. OpenStax adds that barrier mechanisms such as mucus and the skin surface work continuously, rather than starting only after infection.

The immune system is not one organ or a single measure of strength. IQWiG describes organs, cells and proteins working together. This overview cannot judge a person's immune function from how they feel or from one laboratory result.

Evidence: NIAID: overview of the immune system / OpenStax Anatomy and Physiology 2e: innate defence and inflammation / IQWiG InformedHealth: how the immune system works

#Innate and adaptive responses work together

NIAID distinguishes a relatively rapid, broad innate response from the more specific adaptive response. Innate cells recognise general patterns associated with microbes or tissue damage and help activate adaptive cells. Adaptive B and T cells have receptors that recognise particular antigens, which can come from microbes, the body's own cells or allergens.

B cells can produce antibodies, while T cells have roles that include killing infected cells and coordinating other immune cells. These are interacting mechanisms, not two independent shields. The explanation does not determine whether someone needs immune testing or a particular treatment.

Evidence: NIAID: features of an immune response / MedlinePlus: immune response

#Memory and regulation shape later responses

NIAID describes some activated B and T cells being retained as memory cells after a response. On a later encounter with the same pathogen, these cells are already prepared to respond. Immune responses also need control: inadequate responses can fail to limit infection, while inappropriate or continuing responses can cause harm.

Immune memory is a biological mechanism, not a guarantee that an individual cannot become ill again. Nor does more immune activity always mean better health. This page evaluates no immune-boosting product and provides no personal vaccine schedule, allergy assessment or autoimmune diagnosis.

Evidence: NIAID: features of an immune response / NIAID: overview of the immune system

Source note

The sections above were checked against the linked sources. No clinical review has been performed. This is general research education, not a clinical guideline.