From the Guidelines
The elevated level of Immunoglobulin G Subclass 2 (IgG2) at 709 mg/dL is not necessarily indicative of an immune system abnormality or inflammatory condition, as approximately 2.5% of the population will automatically be "deficient" or have elevated levels of at least one IgG subclass due to the definition of normal IgG subclass values being within 2 SDs of the mean 1. This elevation could be a benign finding, and its clinical significance should be interpreted in the context of your overall health, symptoms, and other laboratory results.
- IgG2 is one of four IgG subclasses and primarily responds to polysaccharide antigens like those found in bacterial cell walls.
- Elevated IgG2 levels may be associated with chronic infections, autoimmune disorders, liver diseases, or certain types of blood cancers like multiple myeloma or lymphoma, but this is not always the case.
- A single elevated measurement of IgG2 is not sufficient to diagnose an immune system abnormality, and follow-up testing may be necessary to confirm any potential issues 1. It is essential to follow up with your healthcare provider to determine the clinical significance of this elevation and whether additional testing or monitoring is needed, as the diagnosis of antibody deficiency, including IgG subclass deficiency, is controversial and requires careful evaluation 1. Your doctor might consider your medical history, current symptoms, and possibly order additional tests to identify the underlying cause of the elevated IgG2 level.
- The use of immunoglobulin replacement therapy for subjects with IgG subclass deficiency is also a topic of controversy, and a significant number of subjects may have been started on this therapy erroneously 1.
- Establishing diagnostic criteria for antibody deficiency is crucial to avoid unnecessary treatment, and a consensus opinion among experts is necessary to ensure that patients receive appropriate care 1.
From the Research
Interpretation of Immunoglobulin G Subclass 2 Result
- The result of 709 mg/dL for Immunoglobulin G Subclass 2 is above the normal range of 124 - 549 mg/dL.
- According to the study 2, measurement of IgG subclass concentrations is useful for diagnosis of IgG subclass deficiency and can aid in the diagnosis of specific antibody deficiency.
- However, the study 3 suggests that IgG subclass measurement is not very helpful in the general assessment of immune function, as it provides no information about the patient's capacity to produce specific antibodies to protein, polysaccharide, or viral antigens.
- The study 4 characterized adult patients with IgG subclass deficiency and subnormal IgG2, but the result of 709 mg/dL is actually above the normal range, not subnormal.
- The study 5 discusses the structure and effector functions of IgG subclasses, including IgG2, but does not provide direct information on the interpretation of elevated IgG2 levels.
- The study 6 found that suboptimal serum IgG2 levels could increase susceptibility to late-onset bacterial pneumonia after allogeneic HSCT, but the result of 709 mg/dL is above the normal range, not suboptimal.
Possible Implications
- Elevated IgG2 levels may not be directly associated with a specific disease or condition, as the studies 2, 3, and 5 do not provide clear information on the implications of elevated IgG2 levels.
- However, the study 4 suggests that IgG subclass deficiencies can be associated with various immunologic abnormalities, and it is possible that elevated IgG2 levels may be related to other immunologic conditions.
- Further evaluation and consultation with a healthcare professional are necessary to determine the significance of the elevated IgG2 level and to rule out any underlying conditions.