Deviations of IgG subclass serum levels in immunodeficiency syndromes
IgG subclass deficiency is a common feature in a number of primary as well as secondary immunodeficiency syndromes. The primary immunodeficiency diseases are the naturally occurring defects of the immune system. These primary defects may read to recurrent protozoal, bacterial, fungal and viral infections of varying severity. The immune system can also be adversely affected secondarily by a variety of pathological conditions (including malignancy, metabolic diseases and malnutrition) and drugs; these result in secondary immunodeficiencies. Primary aswell as secondary immunodeficiencies may result in recurrent or persistent infections. A selective deficiency of one or more IgG subclasses may in itself present a primary immunodeficiency syndrome.
In table V and VI, a few examples are given of primary and secondary immunodeficiency diseases in which IgG subclass deficiencies may occur.
Table V: IgG Subclass in primary immunodeficiency syndromes
| Primary immunodeficiency: | IgG Subclass deficiencies: |
| IgA deficiency (71,72) | frequently associated with IgG2 and IgG4 deficiencies but IgG3 deficiencies may also occur as well |
| Common Variable Immunodeficiency (CVID) (73,74) | associated with decreased levels of IgG1, IgG2 and IgG4 |
| Wiskott-Aldrich Syndrome (WAS) (75,76) | IgG3 and IgG4 deficiencies are observed |
| Ataxia telangiectasia (77,78) | IgG2 and IgG4 levels are usually very low, sometimes also associated with IgG3 deficiency |
| Chronic Mucocutaneous Candidiasis (79) | some patients have IgG2 and IgG4 deficiency, isolated IgG2 and IgG3 deficiencies are also observed |
TABLE VI: IgG Subclasses in secondary immunodeficiency syndromes:
| Secondary immunodeficiency: | IgG subclass deficiencies |
| HIV-infection (stages III and IV) (80,81,82) | IgG2 and IgG4 levels are often decreased, while levels of IgG1 and IgG3 are increased |
| Radiation exposure, chemotherapy (83,84) (bone-marrow transplantation) | often associated with low levels of IgG2 and IgG4 |