Immunoglobulin G (IgG) Subclass 2 Concentration (Serum)

What Does IgG2 Serve in the Body?

IgG2 antibodies are a key part of your immune response, particularly against encapsulated bacteria like *Streptococcus pneumoniae* and *Haemophilus influenzae*. They also play a role in defending against some viruses and certain allergens. Unlike other IgG subclasses, IgG2 is less effective at neutralizing toxins but is crucial for opsonization (marking pathogens for destruction by immune cells).

When Might You Need This Test?

Doctors may order an IgG2 test if you have recurrent infections, particularly those caused by bacteria that are typically well-protected by IgG2, or if you have conditions like common variable immunodeficiency (CVID), where immune function is weakened. It may also be checked in research or diagnostic workups for immune-related disorders.

What to Expect During the Test

A blood sample will be drawn from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The sample is then sent to a lab for analysis. Results are typically available within a few days.

Common Reasons for Abnormal Results

Low IgG2 levels may suggest an immune deficiency or a condition that affects antibody production, such as CVID or certain autoimmune diseases. High levels could indicate chronic infections, certain cancers, or other immune system responses. Always discuss results with your healthcare provider.