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Opsonin Antibody (Serum) – Qualitative Immunoassay

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

This test measures whether your blood contains antibodies that may help your immune system identify and attack certain bacteria. Antibodies like opsonins can help your immune system tag pathogens for destruction.

Quick summary

["This screening helps identify potential immune responses to specific bacterial infections that may require further evaluation."]

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

Key facts at a glance

LOINC
23256-1
Short code
Mp bovis Ab Ser Ql CF
Synonyms
Mp bovis Ab Ser Ql CF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
comp-fix
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 This Test Measures

Opsonin antibodies are part of your immune system’s defense mechanism. They bind to bacteria (like *Streptococcus pneumoniae* or *Haemophilus influenzae*) to mark them for destruction by white blood cells. This test detects the presence of these antibodies in your serum using an immunoassay method.

Why It Might Be Ordered

Your healthcare provider may order this test if you have symptoms of infection (e.g., fever, fatigue, or respiratory issues) or if you’re at higher risk for certain bacterial infections (e.g., pneumonia, meningitis). It can also be part of a broader immune evaluation.

How the Test Works

A small blood sample is drawn and tested for the presence of opsonin antibodies. The immunoassay detects antibody levels qualitatively (yes/no presence), not their exact concentration.

What to Expect Before the Test

No special preparation is needed. Wear comfortable clothing, and arrange for someone to drive you home if you feel dizzy after the draw.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Opsonin Antibody (Serum) – Antibody Screening

Frequently asked questions

This test helps rule out or confirm certain immune-related infections. Positive results may indicate past exposure or an active immune response, guiding further testing (e.g., cultures) or treatment decisions.
A positive result suggests your immune system has detected and responded to specific bacteria, but it doesn’t confirm an active infection. Follow-up may include cultures or additional antibody tests.
What does a positive result mean?
A positive result means your blood contains antibodies targeting opsonins, which could indicate prior exposure to those bacteria or an ongoing immune response. This doesn’t always mean you’re currently infected but may prompt further evaluation.
Can this test be used to diagnose an active infection?
No, this test is a screening tool. For diagnosing an active infection, your provider may use cultures, imaging, or other tests to identify the bacteria causing symptoms.
  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