By affected component •
Humoral immune deficiency (including B cell deficiency or dysfunction), with signs or symptoms depending on the cause, but generally include signs of
hypogammaglobulinemia (decrease of one or more types of antibodies) with presentations including repeated mild
respiratory infections, and/or
agammaglobulinemia (lack of all or most antibody production) which results in frequent severe infections and is often fatal. •
T cell deficiency, often causes secondary disorders such as
acquired immune deficiency syndrome (AIDS). •
Granulocyte deficiency, including decreased numbers of
granulocytes (called as
granulocytopenia or, if absent,
agranulocytosis) such as of
neutrophil granulocytes (termed
neutropenia). Granulocyte deficiencies also include decreased function of individual granulocytes, such as in
chronic granulomatous disease. •
Asplenia, where there is no function of the
spleen •
Complement deficiency is where the function of the
complement system is deficient In reality, immunodeficiency often affects multiple components, with notable examples including
severe combined immunodeficiency (primary) and
acquired immune deficiency syndrome (secondary).
Primary or secondary The distinction between primary and secondary immunodeficiencies is based on whether the cause originates in the immune system itself or insufficiency of a supporting component or an external factor.
Primary immunodeficiency Several
rare diseases increase susceptibility to
infections from childhood onward. Primary immunodeficiency is also known as congenital immunodeficiency. Many of these disorders are
hereditary and are
autosomal recessive or
X-linked. There are over 95 recognised primary immunodeficiency syndromes; they are generally grouped by the part of the immune system that is malfunctioning, such as
lymphocytes or
granulocytes. The treatment of primary immunodeficiencies depends on the nature of the defect. It may involve antibody infusions, long-term antibiotics, and, in some cases,
stem cell transplantation. The characteristics of lacking and/or impaired antibody functions can be related to illnesses such as X-Linked Agammaglobulinemia and Common Variable Immune Deficiency
Secondary immunodeficiencies Secondary immunodeficiencies, also known as acquired immunodeficiencies, can result from various
immunosuppressive agents, for example,
malnutrition,
aging, particular medications (e.g.,
chemotherapy,
disease-modifying antirheumatic drugs,
immunosuppressive drugs after
organ transplants,
glucocorticoids) and
environmental toxins like
mercury and other
heavy metals,
pesticides and
petrochemicals like
styrene,
dichlorobenzene,
xylene, and
ethylphenol. For medications, the term
immunosuppression generally refers to both beneficial and potential adverse effects of decreasing the immune system's functions. The term
immunodeficiency generally refers solely to the adverse effect of increased risk of infection. Many specific diseases directly or indirectly cause immunosuppression. This includes many types of
cancer, particularly those of the bone marrow and blood cells (
leukemia,
lymphoma,
multiple myeloma), and certain chronic infections. Immunodeficiency is also the hallmark of
acquired immunodeficiency syndrome (AIDS), ==Causes==