Immunoglobulin G (IgG) Subclass 2 Quantification (Serum)

What Does This Test Measure?

IgG2 is one of five subclasses of Immunoglobulin G (IgG), a key part of your immune system. While IgG overall is important for defending against infections, IgG2 specifically plays a role in responding to certain pathogens, such as some bacteria. Your body produces IgG2 in response to repeated exposure to these pathogens, helping to create long-term immunity. This test helps doctors assess whether your immune system is producing enough IgG2 to fight specific infections effectively.

Why Might You Need This Test?

Doctors may order an IgG2 test if you have a history of recurrent infections, particularly those caused by bacteria like *Streptococcus pneumoniae* or *Haemophilus influenzae*. It can also be used to monitor immune function in conditions like common variable immunodeficiency (CVID) or other immune disorders. Sometimes, it’s part of a broader evaluation if you’ve had unexplained symptoms related to immune function.

How Is the Test Performed?

A blood sample is drawn from a vein in your arm. The blood is then sent to a lab, where it’s processed to separate the serum (the liquid part without blood cells). The lab uses an immunoassay method to measure the amount of IgG2 antibodies in the serum. This test does not require fasting or special preparation beyond standard blood draw guidelines.

What Do Results Mean?

Results are reported as a concentration of IgG2 in the serum, typically in milligrams per deciliter (mg/dL). While reference ranges can vary slightly between labs, a low IgG2 level may suggest an immune deficiency that could affect your ability to fight certain infections. High levels might be seen in certain chronic infections or autoimmune conditions, but this is less common for IgG2 alone. Your doctor will interpret results in the context of your overall health and medical history.