Your immune system, which consists of special cells, organs, and lymphatic system, works together to provide defense against infections and other harmful invaders that can make you sick. Lymphatic vessels are thin tubes that branch throughout your body, just like blood vessels. Lymphatic vessels carry a clear fluid called lymph that takes away waste products from your body. Your immune system also includes your skin that prevents germs from getting into the body, mucous membrane that traps and fights germs, and white blood cells which fight microbes.
You have three types of immunities, viz. innate immunity, active immunity, and passive immunity. Innate immunity is your first line of defense that keeps harmful substances from entering your body. You are born with your innate immunity. Your body develops active immunity when you are infected or vaccinated against foreign substances. For many diseases, you develop active immunity for a lifetime. You develop passive immunity when you receive antibodies for a disease, instead of making them through your own immune system, such as through blood products containing antibodies.
Your immune system can also overreact to certain allergens and cause many diseases, like asthma can be triggered by common allergens like dust or pollens. Allergic rhinitis is caused by your immune system’s overreaction to indoor allergens like dust and pets, and outdoor allergens like molds and pollens. The condition is characterized by a runny nose, sniffing, sneezing and swelling of your nasal passage.
Severe combined immunodeficiency (SCID)
Severe combined immunodeficiency (SCID) is an autoimmune system disorder which is present at birth. Children are in constant danger of infections from germs, microbes, bacteria and viruses. Children with SCID have a low count or missing white blood cells. Your immune system can also be temporarily weakened by taking certain medications, like medications for chemotherapy. Your immunity can also be compromised due to alcohol, smoking, poor nutrition, or after organ transplant due to medications taken to prevent organ rejection.
When your immune system recognizes an antigen, your body calls for an immune response, and part of this response is antibodies that attack, weaken and destroy antigens. Afterward, your immune system remembers the antigen, and when the antigen is detected again by your immune system, it will send the right antibodies to fight them, and protect you from getting sick.
Diseases of the autoimmune system
Your autoimmune system can be harmed due to Type 1 diabetes wherein it attacks cells in the pancreas that make insulin, mistaking them to be as invading intruders. Insulin removes sugar from your body to use as energy. Rheumatoid arthritis causes swelling and deformities of the joints. People with autoimmune system diseases are at an increased risk of lupus disease that attacks lungs, kidneys, skin and body tissues. In inflammatory bowel disease (IBD), your immune system attacks the lining of your intestine, causing episodes of diarrhea, bowel movement, abdominal pain, and weight loss.
In psoriasis, your immune system collects T-cells from your body in the skin, producing silvery and scaly plaques on the skin. Hashimoto’s thyroiditis is when antibodies produced by your immune system attack the thyroid gland, slowly destroying the cells that produce thyroid hormone.
Diagnosis and treatment
Immune system diseases are diagnosed by blood tests and prenatal testing. Treatments are provided by administering antibiotics. In immunoglobulin therapy, antibody proteins are administered in the body to help it fight infections. Stem cell transplantation offers a permanent cure for many types of immunodeficiency that can be life-threatening. In gene therapy, the patient’s stem cells are taken out which are then corrected and returned to the patient through intravenous infusion.