Immune Deficiency or "weak" Immune System
What is an immunodeficiency?
This is an inherited (or sometimes acquired) defect involving the immune system predisposing the individual to frequent and more severe infections, immune dysregulation causing autoimmune disease and sometimes malignancy. In other words, some part of your immune system does not work correctly because you were born without that part (inherited) or as a result of some process that has happed during your life (acquired, like an infection with the AIDS virus).
The immune system is composed of two big components: the immune cells and the immune proteins. The immune cells are all part of the white blood cells and most importantly involve cells call T cells, and B cells. T cells are like the conductor in an orchestra and they direct the traffic of all the other cells. Some of these cells are required for the immune system to work normally as these T cells help with the other parts of the immune system. The B cells are the cells that make the major immune protein that fights baterial infections called antibodies (or immunoglobulins). A third type of white blood cell is called the phagocyte, which means "the cell that eats". These phagocytes are the foot soldiers of the immune system and are the cells that attack invades and literally eat them and digest them. These are the cells that make the puss when you get a sliver in your hand. Finally, another important protein in your blood that is important for the immune system is called complement proteins. These proteins float around and then attach to something that is "foreign" (like bacteria) placing a red flag for the other white blood cells to find something to attack.
Summary of immune components:
- T-cells: important helper cells for the immune system, "the conductor"
- B-Cells: important source of antibodies
- Phagocytes: the foot soldier to gobble up all invaders.
- Antibodies (immunoglobulins): special proteins that fight bacterial infections
- Complement: special proteins that mark invades for attack
Inherited immune defects:
The inherited immunodeficiency syndromes may be classified into 5 major categories depending of what part of the immune system is involved.
1. Antibody or B cell disorders (50-65%)
2. Cellular or T-cell disorders (5-10%)
3. Combined B and T cell disorders (20-25%)
4. Phagocytic disorders (10-15%)
5. Complement deficiencies (<2%)
Common misconceptions about immunodeficiency disorders are: (1) only infants and young children are affected; (some I.D. disorders are seen predominantly in adults such as Common Variable Immune Deficiency (CVID) and IgA deficiency); (2) a physician rarely encounters a patient with I.D; (unless there is a strong index of suspicion, the diagnosis may be missed); (3)someone with I.D. will usually present with severe illness and only then would the diagnosis be considered (in adults, signs of I.D. may often be subtle).
To confuse the issue, in a general allergy practice, many patients with allergies and asthma have recurrent infection especially of the upper (nasal and sinus) and lower (bronchi and lung) airway. What guidelines should the physician use to know when to pursue an immune system evaluation? If a child is exposed to older siblings or children in day care, it is not unusual for the normal child to develop up to 10 upper respiratory infections per year, especially if the child has allergies.
So when do I worry about immune deficiency?
Suspect I.D. in the following situations: (1) Family history of immunodeficiency or unexplained early childhood deaths; (2) Prolonged or frequent infections; (3) Failure to thrive (when a baby or child fails to gain weight or start loosing weight); (4) Unusual or rare pathogenic organisms or infections (Pneumocystis, Candida, Aspergillus, Serratia); (5) 2 or more serious infections over a short time period (meningitis, osteomyelitis, sepsis); (6) unexpected complication of a common infection (mastoiditis with otitis media). Clinical features of I.D. may also include weight loss, fevers, absent lymph nodes and tonsils, presence of liver and spleen enlargement, persistent oral or skin candida infection and severe viral disease such as chickenpox or herpes. Some times the type of the infections is a clue to what type of immune deficiency you may have. It is important to discuss these things with your doctor.
What can I do if I have an immune deficiency?
What treatment is available for the immunodeficiencies? Intravenous or subcutaneous human immunoglobulin (IVIG) are essential in the antibody or B cell disorders such as agammaglobulinemia, and combined I.D. syndromes until more definitive therapy is administered (bone marrow transplant). With this treatment patients are given replacement doses of antibodies or immune globulins. Some patients with immunodeficiencies will require intermittent antibiotic therapy for bacterial infections and sometimes prophylaxis (or long term daily) with antibiotics. Special hormone cytokine replacement such as Interferon gamma and G-CSF has been found useful in certain individual disease states of the phagocytes. Fresh frozen plasma (a component of blood) can temporarily replace complement components in patients with this disorder.
For now the most important thing is to identify if you have an immune defect and then talk to your doctor about the best treatment options. Always use good practices at home, like washing your hands and covering your mouth when you cough. Sometimes, you may even consider wearing a surgical mask during times of high cold and flu risk.