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Line Blot Immunoassay for Immunoglobulin G (IgG) Subclasses (Serum)

Published: August 9, 2026Updated: August 16, 2026

This test measures specific types of Immunoglobulin G (IgG) antibodies in your blood, which are part of your immune system. It helps identify if certain IgG subclasses are too high or too low.

Quick summary

["Understanding your IgG subclass levels can help diagnose or monitor immune-related conditions."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
82408-6
Short code
GM4 IgG+IgM Ser Ql Line blot
Synonyms
GM4 IgG+IgM Ser Ql Line blot
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
line-blot
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Does This Test Measure?

The test detects four main subclasses of IgG antibodies: IgG1, IgG2, IgG3, and IgG4. Each subclass plays a unique role in your immune response. The line blot method uses antibodies specific to each subclass to identify their presence in your serum.

Why Might You Need This Test?

Doctors may order this test if you have symptoms of an immune disorder, such as recurrent infections, autoimmune diseases, or if you’re being treated for conditions that affect antibody production.

How Is the Test Performed?

A blood sample is drawn from a vein in your arm. The serum portion is then tested using a line blot immunoassay, which detects IgG subclasses by binding to them on a membrane.

What Are Common Reasons for Testing?

Common reasons include evaluating immune deficiencies, assessing response to treatments for conditions like rheumatoid arthritis or lupus, diagnosing infections like tuberculosis, or checking for antibody-related diseases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: IgG Subclass Levels Can Indicate Immune Function and Disease Risk

Short name

IgG subclass line blot

Frequently asked questions

How Long Does It Take to Get Results?
Results are typically available within 24 to 48 hours, depending on lab processing times.
What Are Normal Results?
Normal results vary by lab and individual, but imbalances in IgG subclasses may suggest underlying immune issues that require further medical evaluation.
Can I Avoid This Test?
No, this test is often necessary for diagnosing or managing certain immune-related conditions. Follow your doctor’s recommendations for testing.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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 16, 2026. · Read our editorial policy