Immunoglobulin G (IgG) Subclass 2 (IgG2) by Immunoassay, Quantified in Serum
This test measures the amount of a specific type of antibody (IgG2) in your blood. Antibodies help your immune system fight infections and other diseases.
["IgG2 helps protect against certain bacteria and viruses, and low levels may affect immune response."]
Key facts at a glance
- LOINC
- 89348-7
- Short code
- CD27IgDIgM
- Synonyms
- CD27+IgD-IgM+/CD19 cells NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (lavender/purple-top) blood collection tube; sodium heparin (green-top) is an acceptable alternative. Tubes must be filled to manufacturer's stated volume.
- Units
- N/A
- Ref low
- 0.5
- Ref high
- 4
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- Flow cytometry (multi-color immunophenotyping) using CD27, IgD, IgM, and CD19 fluorescently-labeled monoclonal antibodies; reported as percentage of CD19+ B cells or as absolute count via CD45/SSC gating with counting beads.
- CPT
- 86356 (Monoclonal antibody panel for flow cytometry, each additional marker - for individual antibody staining beyond initial panel); commonly billed with 86355 for first marker and 86356 x multiple for additional markers per addended CPT guidance.
- SNOMED
- 416748002 |Flow cytometry (procedure)|; with associated 269929007 |Lymphocyte subset analysis (procedure)|
- Specimen volume
- 3-5 mL of whole blood for adults; minimum 1-2 mL for pediatric samples.
- Stability
- Specimen should be processed within 24 hours of collection when stored at room temperature (18-22°C). If processing is delayed beyond 24 hours, store at 2-8°C and process within 48 hours. Do not freeze whole blood. Viability and surface marker integrity decrease significantly after 48 hours.
- Hemolysis max
- 100
- Lipemia max
- 500
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
What Does This Test Measure?
IgG2 is one of five subclasses of Immunoglobulin G (IgG), the most common antibody in your blood. This test specifically measures the concentration of IgG2, which plays a role in defending against some bacterial infections and certain immune responses. IgG2 antibodies are particularly important for protecting against encapsulated bacteria like Streptococcus pneumoniae and Haemophilus influenzae.
Why Might You Need This Test?
Your healthcare provider may order this test if you have symptoms of a weakened immune system, such as frequent infections, recurrent sinus or ear infections, or if you have conditions like asthma, allergies, or certain autoimmune diseases. It may also be used to monitor immune function in people with HIV/AIDS or other immune-related disorders.
What to Expect Before the Test
No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, similar to other routine blood tests. If you are on blood thinners or have a history of bleeding issues, let your healthcare provider know before the test.
What to Expect During the Test
The blood sample will be taken from a vein in your arm. You may feel a slight pinch when the needle is inserted, but the procedure usually takes just a few minutes. The blood will be sent to a lab for analysis using an immunoassay method to measure IgG2 levels accurately.
Reference range
Reference ranges are laboratory- and age-specific. In healthy adults, CD27+IgD-IgM+ (IgM-only) memory B cells typically constitute approximately 0.5% to 4% of total CD19+ B cells, with reported adult median values around 1-2%. Pediatric reference ranges differ and should be established per laboratory. Results must be interpreted in conjunction with the full B-cell subset panel.N/A
No special patient preparation required. Patients on active immunosuppressive or B-cell-depleting therapy (e.g., rituximab, corticosteroids, chemotherapy) may have altered subset distribution; document recent medications and timing of last infusion. Avoid testing within 24-48 hours after recent vaccination when feasible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
IgG2 Level
Frequently asked questions
IgG2 levels can be lower than normal in people with certain immune deficiencies, such as selective IgA deficiency or common variable immunodeficiency. Low IgG2 levels may also be associated with conditions like asthma, allergies, or autoimmune diseases. Conversely, very high levels may rarely be seen in certain immune disorders or chronic infections.
Normal IgG2 levels vary and are not strictly defined by a single range. Your results will be compared to your own baseline or to reference ranges provided by your healthcare provider. They may consider clinical context, such as your symptoms and medical history, when interpreting your results.
Yes, IgG2 levels can fluctuate due to various factors, including age, immune response to infections, medications, or underlying health conditions. Regular monitoring may be recommended if you have a condition affecting your immune system.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 11, 2026. · Read our editorial policy