Allergies and Autoimmune disorders

Our immune system is incredible in its complexity and efficiency . However, occasionally, stuff goes wrong. Your body many initiate an immune response to an injury such as a sprain or over-respond to a foreign body, such as pollen and the hay fever that comes with it, or at the more severe end of the scale, fail to recognise self cells as self and begin to attack them, such as some forms of arthritis.

Autoimmune Disorders

It is not clear why the immune system initiates a response against its own tissues in the case of autoimmune disorders. In some cases foreign pathogens and antigens the body has been previously exposed to are similar in structure to some of our body’s own protein markers which can cause immune cells to ‘see’ these cells and tissues as foreign and commence an immune response by attacking them. Rheumatoid arthritis is an autoimmune disorder that primarily affects synovial joints such as the joints in your fingers and hand. Contracting rheumatic fever earlier in life may lead to the formation of antibodies that later mistakenly attack the connective tissue in your joints causing this type of arthritis. (Note: Not all arthritis is an autoimmune disease. If mentioning this in an exam you must say rheumatoid arthritis)

Autoimmune disorders may cause destruction of tissues, changes in organ function or abnormal organ growth. Examples of autoimmune disorders include Multiple Sclerosis (MS), Type 1 Diabetes and Celiac Disease.

This is not that detailed but the information you are required to retain and regurgitate come exam time is not in that much depth. If you don’t believe me, look at your textbook.

Allergies

Allergies are a term that covers the hypersensitivity response of the body. This is a response that is more severe or exaggerated than a response that is considered normal and differs from person to person. The reactions to an allergen is a response to immunological memory – your body remembers these antigens and renewed exposure triggers a fast and massive response. Come spring when the warm northerly winds bring high levels of pollen south to Melbourne, there is a dramatic increase in the cases of hay fever. It works like this: your body develops specific IgE on lymphocytes in response to first exposure to the pollen (or any other antigen). The next year when the winds blow the pollen south again the lymphocytes rapidly produce a large number of antibodies that are secreted and attach to mast cells. When the antibody-attached mast cells come in contact with the pollen the mast cells rupture releasing histamine, triggering an inflammatory response. Swelling of the tissues around the eyes, nose and throat, excessive mucus production, itchiness and all the other symptoms of hay fever. In an allergic or hypersensitive person this reaction is much more severe.

To counter these reactions we take antihistamines which reduce the impact of the inflammatory response and the symptoms of hay fever but blocking the body'd histamine receptors.

This animation shows histamine being released from a mast cell in response to pollen

This is a better animation in response to venom such as a bee sting

(I've just quickly rewritten this while supervising a test - original article was way too detailed. While this is short and brief, it is what you need to know. Hope it helps)


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And, on a completely different topic, here is a herd of 30 pygmy elephants and a group of 25 excited students. This trip to Malaysia left 6 months ago today...