Immunodeficiency disorders refer to conditions where the immune system fails to effectively combat infections and tumors. These disorders can be caused by inherited or congenital defects or may result from acquired diseases. As a consequence, affected individuals experience persistent or recurring infections, often with organisms that would not typically cause disease, and an increased vulnerability to certain types of cancer. Opportunistic infections, such as pneumocystic pneumonia, fungal infections, and widespread herpes simplex infections, are common in individuals with immunodeficiency disorders.
Congenital or inherited deficiencies can manifest in either one of the two branches of the adaptive immune system – humoral immunity or cellular immunity – or in both.
The humoral system deficiencies encompass hypogammaglobulinemia and agammaglobulinemia. Hypogammaglobulinemia may result in minimal or no symptoms, depending on the extent of the deficiency. In contrast, agammaglobulinemia can be life-threatening if left untreated without immunoglobulin therapy.
Inherent deficiencies in T-lymphocytes, a type of white blood cell, can result in health complications like persistent and widespread yeast infections, also known as thrush. A more severe condition, termed severe combined immunodeficiency (SCID), occurs when both the humoral (fluid) and cellular parts of the immune system are deficient. SCID is typically lethal within the first year of a child’s life unless a bone marrow transplant, a potential treatment, is successfully administered.
Acquired immunodeficiency can be a result of various health issues, including HIV infection which leads to AIDS. It can also be caused by harm to the immune system due to its suppression by drugs, a scenario that might be intentional in cases of autoimmune diseases or post-organ transplant, or it may be an unintended side effect while treating another condition. Additionally, severe malnutrition and various types of cancers can lead to a weakened immune system. Mild immunodeficiency can also occur naturally as the immune defenses decline with age.