A person who is immunodeficient has an immune system that not working as it should be, and would not be considered immunocompetent.
The Immune System
Humans have complex immune systems that protect against infectious diseases. To function properly, the body’s immune system must be able to recognize harmful pathogens such as bacteria, viruses, and parasites and send immune cells and proteins to fight the invading pathogen.
Your genes also determine which non-pathogen foreign substances your immune system will be able to recognize and resist, such as tissue from an organ transplant or blood transfusion.
Since pathogens can quickly change and adapt, they can sometimes avoid detection by the immune system. When this happens, you can feel sick or run down and have a hard time fighting off the illness that has taken over your body.
Fortunately, your immune system has many different defense mechanisms and responses to recognize and neutralize pathogens.
Your immune system can respond to pathogens in 2 ways:
Cell-mediated immune response where T-lymphocytes (T-cells—a type of white blood cell) play a central role in recognizing and binding to certain cells such as virus-infected cells and cancer cells displaying tumor antigens (antigens are proteins found on pathogens). Humoral immune response of the B-lymphocytes (or B-Cells) and plasma cells (white blood cells that secrete large amounts of antibodies) protects against bacteria and viruses in the fluids of the body by producing antibodies to fight them.
Your immune system also remembers specific pathogens after fighting them off. This is how you build immunity to some viruses after receiving a vaccine for that particular virus.
What If You Are Not Immunocompetent?
Immunodeficiency is having a compromised immune system. This is often used synonymously with immunosuppression and immunocompromise and can be thought of as primary or secondary.
Primary immunodeficiency or altered immunocompetence is something that you are born with and is generally inherited. Examples include severe combined immunodeficiency (SCID) and other primary antibody deficiency disorders. Secondary immunodeficiency or altered immunocompetence is due to another health condition, like an immunosuppressant drug, an infectious disease such as AIDS, certain cancers, or an accident that damages the spleen.
People who have any primary or secondary immune system problems should not receive live, attenuated vaccines—whether viral or bacterial. Also, inactivated vaccines usually only offer full benefits to immunocompetent patients.
Autoimmune Disorders
When the immune system is altered, it can lead to serious consequences. Normally, the immune system only reacts to invaders (not to antigens from a person’s own tissues), but sometimes the immune system can malfunction and treat the body’s own tissues as foreign—constituting an autoimmune disorder.
An autoimmune reaction is when the immune system produces antibodies (called autoantibodies) or immune cells that attack the body’s own tissues. This causes inflammation and can damage healthy tissue.
People who have autoimmune disorders have antibodies that attack specific tissue types—such as joints, nerves, or specific organs.
Some common autoimmune disorders:
Graves disease Rheumatoid arthritis Hashimoto thyroiditis Type I diabetes Lupus Vasculitis
Further testing by a physician would be required to properly diagnose an autoimmune disorder.
