Histamine intolerance, sometimes called histaminosis, is an over-accumulation of histamine in the human body. Histamine intolerance is sometimes informally called an allergy; however, the intolerance is technically caused by the gradual accumulation of extracellular histamine due to an imbalance.
The imbalance in histamine intolerance is between the synthesis and selective release of histamine from certain granulocytes (i.e., mast cells and basophils), versus the breakdown of histamine by the enzymes which metabolize it, such as diamine oxidase (DAO) and histamine N-methyltransferase (HNMT).
In contrast, allergic reactions involving an immediate allergic response to an allergen are caused by anaphylactic degranulation, which is the abrupt and explosive release of "pre-formed mediators", including histamine, from mast cells and basophils throughout the body.
- Maintz, L.; Novak, N. (2007). "Histamine and histamine intolerance". American Journal of Clinical Nutrition. 85 (5): 1185–96. PMID 17490952.
- Moon TC, Befus AD, Kulka M (2014). "Mast cell mediators: their differential release and the secretory pathways involved". Front Immunol. 5: 569. doi:10.3389/fimmu.2014.00569. PMC 4231949. PMID 25452755.
This release of pre-formed mediators enables not only rapid anaphylactic reactions and allergic responses but also initiates recruitment of leukocytes to sites of pathogen invasion, activation of innate immune processes, and inflammatory responses (1). ... Two types of degranulation have been described for MC: piecemeal degranulation (PMD) and anaphylactic degranulation (AND) (Figures 1 and 2). Both PMD and AND occur in vivo, ex vivo, and in vitro in MC in human (78–82), mouse (83), and rat (84). PMD is selective release of portions of the granule contents, without granule-to-granule and/or granule-to-plasma membrane fusions. ... In contrast to PMD, AND is the explosive release of granule contents or entire granules to the outside of cells after granule-to-granule and/or granule-to-plasma membrane fusions (Figures 1 and 2).
Figure 1: Mediator release from mast cells
Figure 2: Model of genesis of mast cell secretory granules
Figure 3: Lipid body biogenesis
Table 2: Stimuli-selective mediator release from mast cells