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The immune system is made up of a complex network of organs, cells and proteins that fight infection (microbes). The immune system and microbial infectionThe immune keeps a record of every microbe it has ever defeated, in types of white blood cells (B-lymphocytes and T-lymphocytes) known as memory cells. This means it can recognise and destroy the microbe quickly if it enters the body again, before it can multiply and make you feel sick. Some infections, like the flu and the common cold, have to be fought many times because so many different viruses or strains of the same type of virus can cause these illnesses. Catching a cold or flu from one virus does not give you immunity against the others. Parts of the immune systemThe main parts of the immune system are: White blood cellsWhite blood cells are the key players in your immune system. They are made in your bone marrow and are part of the lymphatic system. White blood cells move through blood and tissue throughout your body, looking for foreign invaders (microbes) such as bacteria, viruses, parasites and fungi. When they find them, they launch an immune attack. White blood cells include lymphocytes (such as B-cells, T-cells and natural killer cells), and many other types of immune cells. AntibodiesAntibodies help the body to fight microbes or the toxins (poisons) they produce. They do this by recognising substances called antigens on the surface of the microbe, or in the chemicals they produce, which mark the microbe or toxin as being foreign. The antibodies then mark these antigens for destruction. There are many cells, proteins and chemicals involved in this attack. Complement systemThe complement system is made up of proteins whose actions complement the work done by antibodies. Lymphatic systemThe lymphatic system is a network of delicate tubes throughout the body. The main roles of the lymphatic system are to:
The lymphatic system is made up of:
SpleenThe spleen is a blood-filtering organ that removes microbes and destroys old or damaged red blood cells. It also makes disease-fighting components of the immune system (including antibodies and lymphocytes). Bone marrowBone marrow is the spongy tissue found inside your bones. It produces the red blood cells our bodies need to carry oxygen, the white blood cells we use to fight infection, and the platelets we need to help our blood clot. ThymusThe thymus filters and monitors your blood content. It produces the white blood cells called T-lymphocytes. The body's other defences against microbesAs well as the immune system, the body has several other ways to defend itself against microbes, including:
Fever is an immune system responseA rise in body temperature, or fever, can happen with some infections. This is actually an immune system response. A rise in temperature can kill some microbes. Fever also triggers the body's repair process. Common disorders of the immune systemIt is common for people to have an over- or underactive immune system. Overactivity of the immune can take many forms, including: Underactivity of the immune system, also called immunodeficiency, can:
An underactive immune system does not function correctly and makes people vulnerable to infections. It can be life threatening in severe cases. People who have had an organ transplant need immunosuppression treatment to prevent the body from attacking the transplanted organ. Immunoglobulin therapyImmunoglobulins (commonly known as antibodies) are used to treat people who are unable to make enough of their own, or whose antibodies do not work properly. This treatment is known as immunoglobulin replacement therapy . Until recently, immunoglobulin therapy in Australia mostly involved delivery of immunoglobulins through a drip into the vein – known as intravenous immunoglobulin (IVIg) therapy. Now, subcutaneous immunoglobulin (SCIg) can be delivered into the fatty tissue under the skin, which may offer benefits for some patients. This is known as subcutaneous infusion or SCIg therapy. Subcutaneous immunoglobulin is similar to intravenous immunoglobulin. It is made from plasma – the liquid part of blood containing important proteins like antibodies. Download the SCIg introduction fact to read more about this type of treatment. Many health services are now offering SCIg therapy to eligible patients with specific immune conditions. If you are interested, please discuss your particular requirements with your clinical immunology/allergy . ImmunisationImmunisation works by copying the body's natural immune response. A vaccine (a small amount of a specially treated virus, bacterium or toxin) is injected into the body. The body then makes antibodies to it. If a vaccinated person is exposed to the actual virus, bacterium or toxin, they won't get sick because their body will recognise it and know how to attack it successfully. Vaccinations are available against many diseases, including measles and tetanus. The immunisations you may need are decided by your health, age, lifestyle and occupation. Together, these factors are referred to as HALO, which is defined as:
View the HALO to find out more. Where to get help
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