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Chapter 5 Notes
- The immune system is made up of a complex group of cells and organs found throughout the body. The system includes primary organs, such as the thymus gland and the bone marrow, and secondary organs, such as the lymph nodes, spleen, liver, and tonsils. Lymphocytes, the major cells of the immune system, arise and develop in the primary organs. The secondary organs are responsible for filtering foreign substances and providing the space for antigen reactions.
- The cells of the immune system include four types of leukocytes: polymorphonuclear leukocytes, monocytes, macrophages, and lymphocytes.
Types of Immunity
| Type of Immunity | Example |
|---|---|
| Active natural immunity | Having the disease (such as mumps) |
| Active artificial immunity | Receiving a vaccination (such as MMR) |
| Passive natural immunity | Antibodies produced by the body itself or received from maternal–fetus transmission |
| Passive artificial immunity | Injection of antibodies |
- The most important test for diagnosing allergies is the skin test. A skin test may be performed by intradermal injection involving injection of a small amount of the suspected antigen under the skin. A skin patch test utilizes placement of a small antigen-soaked patch placed against the individual’s skin. Another skin test is a scratch test in which a small amount of suspected antigen is placed in a small scratch. All three types of tests are used to identify an allergen.
- A Coombs test will indicate the formation of antibodies on the red blood cell. This test can be used to determine blood type and diagnose certain hemolytic (HE-moh-LIT-ick; hemo = blood, lytic = destroying) anemias. A Coombs test can also indicate the presence of maternal antibodies against the fetal blood type, as occurs in erythroblastosis fetalis.
- Autoimmune disorders can be diagnosed using blood tests that measure for specific diseases. For example, individuals with systemic lupus erythematosus will have a positive antinuclear antibody (ANA) test. Rheumatoid factor (RF) in the blood is often indicative of rheumatoid arthritis. Another test for rheumatoid arthritis is the presence of anti-cyclic citrullinated peptide (anti-CCP) antibodies. This test is also used to predict those who will have more severe effects of the disease.