IgG Subclass 1–4 Immunoassays
Deficiencies of IgG subclasses are an indication of a disturbed immune response and usually lead to clinical symptoms in the patient, although decreased levels of IgG subclasses may also be asymptomatic. However, several disease states are strongly associated with decreased or increased levels of IgG subclasses. Measuring total IgG may only mask deficiencies in subclasses 2, 3, and/or 4 due to a possible high concentration of predominant IgG1.
Therefore, the determination of IgG subclass concentrations has become increasingly important in clinical diagnostics. It is indicated for diagnostic clarification in patients with:
- A malfunctioning immune defense
- Immunoglobulin deficiencies
- Increased susceptibility to infection
- Abnormally frequent and/or prolonged or severe infections that cannot be explained by standard clinical and laboratory data
IgG4-related disease is a relatively new and growing entity of immune-mediated origin, often with multi-organ impairment. Although the diagnosis of this disease must be confirmed histopathologically, serum IgG4 is an important marker in the evaluation and longitudinal assessment. Diagnostic delays in the setting of IgG4-related disease can lead to cirrhosis, pancreatic failure, advanced renal dysfunction, and many other complications.
Therapy with glucocorticoids is considered a first choice with very good patient outcomes. If this therapy is used, it should be monitored over a certain period (12 months recommended by guidelines) by measuring serum IgG4 for evaluation of treatment or detection of relapse.