Immune System, Digestion and Food Allergies
As mentioned previously, several organs are involved in the digestive system's ability to keep itself healthy. These include the salivary glands, which secrete amylase, the stomach, which secretes acid, the Peyer patches in the small intestine, and the white blood cells in the lymphatic system and the circulatory system. The white cells are notably vital in protecting the body from disease. When a substance is first recognized as foreign, it is ingested by white blood cells called macrophages. These macrophages present the antigen to another type of white blood cells made by the thymus called helper T cells. The helper T cells secrete chemicals called cytokines when they recognize that a substance is foreign. These cytokines tell another type of white blood cells also made by the thymus (cytotoxic T cells) to destroy the substance. Also, helper T cells stimulate white blood cells made by the bone marrow (B cells). The B cells secrete chemicals called antibodies in response to a foreign substance. These antibodies destroy the substance. Thus several different white blood cells work together to ensure that microbes are destroyed once they enter.
However, sometimes the macrophages view a substance that is not a microbe as unsafe and ingest it. They present the antigen to the helper T cells, which activate the B cells. The B cells then secrete antibodies to destroy the substance. This can produce an immune response associated with food intolerance or food allergies. For instance, in celiac disease, the macrophages in the mucosa of the intestine present a peptide called gliadin, which is found in wheat products, to the helper T cells. As a result, large numbers of B cells and other cells that are senstitve to gliadin arrive at the site and travel into the epithelium, damaging it.
Although the macrophages, the T cells, and the B cells can cause an allergic reaction to food, not all food allergies are caused by them. For instance, shellfish and cheese can cause an allergic reaction without intervention from the white blood cells though direct release of histamine. Therefore, a number of factors may affect food allergies.Last Updated: Saturday, July 16, 2011