Eosinophils are important immune cells in the gut. Eosinophils are important effector cells in the immune system. They play a useful role in host defense against nematode and other parasitic infections and are active players in many immune responses. However, eosinophils can also be detrimental as part of the inflammatory process in allergic disease.
In addition, eosinophils can help keep the immune system in balance. They help control the response to foreign antigens (structures to which antibodies bind). This includes food and microorganisms (both harmful and beneficial, such as the microbiome). Eosinophils also help prevent immune cells from attacking endogenous tissues [2, 16].Eosinophils are granulocytes of the innate immune system best known for their cytotoxic effector function, causing damage to parasitic pathogens in helminth infections and host tissue in allergic diseases.
However, recent data paint a more complex picture, revealing additional roles for eosinophils in regulating inflammation, maintaining epithelial barrier function, influencing tissue remodeling, and linking innate and adaptive immunity. Many of these functions result from the ability of eosinophils to store pre-formed pools of cytokines, chemokines, and growth factors that can be released immediately.
Intestinal infections can occur when eosinophils are not functioning properly.
In addition, many tissue-invasive parasites reside in the gut and migrate through eosinophil-producing tissues only during certain periods of their life cycle. Furthermore, eosinophilia tends to decrease in chronically infected individuals as the host adapts to the presence of the parasite. For common parasites (eg, Strongyloides, hookworm), the negative predictive value of a normal eosinophil count is low. Therefore, a normal eosinophil count does not necessarily rule out parasitic infection.Blood levels of eosinophils may be elevated in inflammatory bowel disease, but the role of eosinophils in gastrointestinal disease remains to be elucidated. For example, in patients with active ulcerative colitis, tissue levels of the eosinophil-recruited chemokine eotaxin-1 correlate with tissue eosinophilia. 18 In a retrospective cohort of sarcoidosis, mild peripheral eosinophilia was common in sarcoidosis-patients even in the absence of another atopic disease. 19
In IgG4-related disease, a relatively new disease known to cause tissue infiltration and tumor-like destruction of certain glands, organs, and lymph nodes, blood eosinophilia may be present in approximately 25% of patients, and IgE Elevated and mild-to-moderate blood eosinophilia occurred independently of atopy. 20Eosinophilia develops as immune-mediated responses associated with various processes. It has been found to be associated with various atopic diseases, drug-induced hypersensitivity reactions, collagen vascular diseases, and malignancies.
Eosinophilia is also particularly associated with helminth infections, especially at this developmental stage in which they invade host tissues. Infections are usually chronic, with high rates of reinfection and diffuse features, with patterns of intense infection limited to a minority of the general population [7.
