Immune System
The immune system is responsible for protecting the body against abnormal cells, such as tumor cells, invading pathogens including viruses, bacteria, and parasites and other foreign particles. The major parts of the immune system include:
- The lymphatic system (including white blood cells)
- The thymus
- The spleen
The white blood cells (WBC’s) are the first line of defense within the immune system. When the body (self) recognizes an abnormal cell or invading pathogen (non-self) the WBC’s initiate an attack to destroy the invader. Different types of WBC’s perform specific functions; one type ‘eats’ the invader (this process is called phagocytosis), while other WBC’s are responsible for creating antibodies, which aid in the destruction of the abnormal cells as well as allow the body will quickly recognize the pathogen in the future. Antibodies that are produced circulate within the blood, and if the pathogen is present, will mark the pathogen so that other WBC’s will recognize and remove the invader. In addition, WBC’s in conjunction with additional cells of the immune system, secrete specialized molecules that choreograph the many phases of the immune response.
Problems arise when the immune system does not function properly. Hematologic disorders including leukemia may cause the immune system to malfunction. There are also times when the body has trouble recognizing “self” from “non self”, resulting in autoimmune disorders.
The following is a short list of the many disorders that may affect the immune system.
- Leukemia
- Cancer
- Tumors
- Immunodeficiency due to:
- HIV infection
- Chemotherapy
- Immunosuppressive drugs after organ transplants
- Autoimmune disorders
- Lupus (SLE)
- Rhumatoid arthritis
- Graves disease