Lowered Immune Response
As pro-inflammatory substances, inflammatory mediators, which include histamine, affect the immune system. Histamine modulates the immune system cells’ maturation, activation, polarization, chemotaxis, and effector activities. Histamine is a potent inflammatory mediator usually linked with allergic responses; it promotes vascular and tissue alterations. During the histamine reaction, inflammatory cytokines are created and circulated throughout the body, resulting in inflammation, allergy symptoms, and in some cases, histamine intolerance. When this mechanism is hyperactive, it may result in persistent, unresolved inflammation and weakened immunity.
Due to the varied expression and regulation of four histamine receptors and their unique intracellular signals, histamine exerts various effects on immune regulation. Continuous exposure to antigenic environmental stimuli is likely to destabilize the immune system. This can increase the body’s susceptibility to infection and autoimmunity. There are two major immunity processes inside the adaptive immune system: Th1, a cell-mediated immunity (not involving antibodies), and Th2, a humoral immunity (involves antibodies). The Th2 response induces the release of histamine, and the cycle continues when this response is hyperactive or unresolved. Consequently, a hyperactive histamine response leads to a reduced Th1 response, an active Th2 response, and an increased risk of viral and bacterial infection.
