Bcellxmserplimp

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

The B cell crossmatch is a blood test performed before organ transplantation to check if the recipient has antibodies that might attack the donor's B cells.

Quick summary

{"Checks for antibodies that could cause organ rejection","A positive result means higher risk of transplant rejection","Performed using blood samples from both donor and recipient","Essential safety test before kidney, liver, or other organ transplants","Results help doctors determine transplant compatibility"}

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

Key facts at a glance

LOINC: 38357-0
Short code: BCMATCH
Synonyms: B Cell XM SerPl-Imp
Category: chemistry
Sample: serum
Container: Serum separator tube (SST) or plain red-top tube for serum; anticoagulated (heparinized or ACD) whole blood for donor lymphocyte preparation
Units: N/A
Fasting: false
Population: adult
Sex: all
Age range: 0–120 years
Method: Complement-dependent cytotoxicity (CDC) crossmatch using donor lymphocytes (T cells and B cells) incubated with recipient serum; flow cytometry crossmatch (FCXM) for B cell crossmatch; interpreted as positive or negative based on cell death or fluorescence shift
CPT: 86825
SNOMED: 127433000
Specimen volume: 10 mL peripheral blood for recipient serum (minimum 3-5 mL); 20-30 mL peripheral blood or lymph node/spleen preparation for donor lymphocytes
Stability: Serum stable for 24 hours at room temperature (20-25°C), up to 7 days at 2-8°C, and up to 1 year frozen at -20°C or colder. Donor lymphocytes must be tested within 24-48 hours of collection; viability must be maintained for accurate results. Avoid repeated freeze-thaw cycles.
Hemolysis max: 500
Lipemia max: 1000
Icterus max: 500
TAT: 4–24 hours
Order: routine

What is this test?

The B cell crossmatch is a laboratory test that checks whether the person receiving an organ (the recipient) has pre-formed antibodies that could react against the donor's B cells. B cells are a type of white blood cell that carry special markers (antigens) on their surface. If the recipient's immune system has already been exposed to these markers—through previous transplants, blood transfusions, or pregnancies—their body may have developed antibodies against them. When these antibodies are present and react with the donor's cells, it is called a 'positive crossmatch,' which means the transplant carries a high risk of being rejected.

During the test, blood samples from both the donor and recipient are mixed together in a laboratory. Technicians then look for signs of an immune reaction, such as cell damage or complement activation. The results are reported as either positive (antibodies present and reactive) or negative (no significant reaction detected).

Reference range

Negative (no donor-specific antibodies detected against B cell antigens). Report includes T cell and B cell crossmatch results with controls; positive B cell crossmatch indicates presence of HLA class I and/or class II antibodies directed at donor antigensN/A

Specimen: serum

No special patient preparation required. Recent blood transfusions (within 72 hours) may yield false-positive results due to passively acquired antibodies. For pre-transplant testing, collect specimen prior to blood transfusion when possible. Inform laboratory of all immunosuppressive therapy and recent desensitization treatments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings2

Frequently asked questions

Why is the B cell crossmatch important before a transplant?

The B cell crossmatch helps doctors determine if your immune system might attack the donated organ. A positive result means you have antibodies that could cause immediate and severe rejection. This test is essential for preventing transplant failure and ensuring patient safety.

What does a positive crossmatch mean?

A positive crossmatch means antibodies in your blood react to the donor's B cells. This indicates a high risk of organ rejection. Your transplant team may need to find a different donor or consider special treatments to reduce antibody levels before proceeding.

Is a negative crossmatch guaranteed to prevent rejection?

No, a negative crossmatch significantly reduces but does not completely eliminate the risk of rejection. Other factors, including tissue typing compatibility and crossmatching for T cells, also play important roles. Regular monitoring after transplantation is still necessary.

How long does it take to get crossmatch results?

Results are typically available within a few hours to 24 hours, depending on the laboratory. In urgent transplant situations, expedited testing may be performed.

Can I still have a transplant if my crossmatch is positive?

In some cases, yes. Your doctor may recommend desensitization treatments, such as plasmapheresis or immunotherapy, to reduce antibody levels. Alternatively, your team may identify a more compatible donor. Each case is evaluated individually based on overall health and urgency.

Sources

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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