Immune systems protect our bodies by producing special proteins called antibodies, which identify potential threats in our bodies. They signal our immune systems to release chemicals to kill these threats. A food allergy occurs when the immune system overreacts and mistakenly identifies proteins in foods as threats, signaling a release of chemicals that cause food reactions to kill them. In most common food allergies, it is the antibody Immunoglobulin E (IgE) that recognizes proteins in foods as threats. It can release many harmful chemicals, including Histamine. Histamine is a main cause for many of the symptoms of allergic reactions, such as small blood vessels expanding, swelling and reddening of surrounding skin, itchiness, and increased mucous production in the nose lining, causing itching and a burning sensation. There is also another type of food allergy called “non-IgE mediated food allergy,” which is caused by different cells in immune systems. These are usually harder to detect because there are no tests to confirm their presence. This type of allergy usually only affects the skin and digestive system. This can lead to symptoms like heartburn, indigestion, and eczema, although, in babies it may also cause diarrhoea and reflux. Antibodies are Y-shaped protein molecules made up of several different regions, all with important parts for when it comes to neutralizing pathogens, among other invaders such as bacteria, viruses, fungi, parasites, and toxins.It is divided into two heavy proteins chains and two light protein chains. These chains are even further divided into three sections as shown in the image: blue, green, and orange. In total, the protein chains include 12 domains.
The heavy protein chains consist of 2 constant domains of CH1, CH2, and CH3 and variable VH, while the light protein chains consist of 2 constant domains of CL and variable VL. The antigen binding site is made up of Complementary Determining Regions’ (CDRs) loops L1, L2, and L3 and loops H1, H2, and H3. But how do antibodies work? There are three ways in which they function. They will either bind to the pathogen to prevent it from damaging other healthy cells, they will stimulate other parts of the immune systems, like complement proteins, to destroy it, or they will mark pathogens through a process called opsonization, allowing other immune cells to identify and attack it. The first method is called Antigen Binding. Antibodies have two antigen binding sites where they attach to antigens. The size and shapes of the finger-like loops determine which pathogens they can grab on to. This is necessary because during Opsonization… both the membranes of the phagocytes that attack the pathogens both have a negative charge, so they naturally repel each other. When they attach, the antibody also attaches its Fc region, or “tail,” to the phagocyte to neutralize the charge so the phagocyte and pathogen can near each other. A typical way pathogens are eliminated during opsonization is through phagocytosis. During phagocytosis, white blood cells surround pathogens, and then pull inside their own membranes to finish them off with enzymes. The problem is that the membranes of the phagocytes and pathogens are both negatively charged, meaning that the repel each other. The antibody is also capable of stimulating the phagocyte, making it more efficient.