What Is the Difference Between HLA-A, HLA-B and HLA-DR?

What Is the Difference Between HLA-A, HLA-B and HLA-DR?

  • Category

    Dermatology

  • Published By

    GetWellGo Team

  • Updated on

    14-Nov-2026

Human Leukocyte Antigens (HLA) is proteins that are found on the surface of most cells in your body. They help your immune system recognise your own cells. HLA typing is an important test that is carried out prior to a Bone Marrow Transplant (BMT). It helps to find a good stem cell donor.

There are three important HLA markers to consider when trying to find a compatible donor for a patient; HLA-A, HLA-B and HLA-DR.

Understanding HLA-A, HLA-B and HLA-DR can help Nigerian patients wanting to have a BMT in India.

In this article we will explain the difference between HLA-A, HLA-B and HLA-DR, how HLA typing works, how much it costs to have the HLA matching test done in India and how Nigerian patients can get HLA typing and donor assessment done.

What is HLA typing?

HLA typing is a laboratory test performed to determine what type of Human Leukocyte Antigen someone has. These are passed down from both parents and are important in the immune system.

HLA typing is performed prior to an allogeneic BMT to see which donor has similar HLA markers to the patient.

This helps to find a donor with a good match to reduce the risk of complications such as graft versus host disease, graft rejection and delayed engraftment.

HLA typing is important for patients with conditions including:

  • Sickle cell disease.

  • Thalassemia major.

  • Aplastic anaemia.

  • Acute myeloid leukaemia (AML).

  • Acute lymphoblastic leukaemia (ALL).

  • Certain lymphomas.

  • Blood and immune related diseases.

The transplant team will decide which HLA markers need to be tested based on the diagnosis and type of transplant.

What is HLA-A?

HLA-A is a Class I Human Leukocyte Antigen. It is found on almost ALL nucleated cells in the body and helps the immune system recognise abnormal/infected cells.

HLA-A presents small protein pieces to immune cells known as CD8+ T-cells. This helps the immune system know which cells may be infected/abnormal.

HLA-A markers will be compared between the patient and potential donor prior to a BMT.

Key points regarding HLA-A:

  • Class I HLA marker.

  • Passed down from both parents.

  • Helps the immune system recognise abnormal/infected cells.

  • One of the important markers to look at when finding a compatible donor.

  • HLA-A markers may affect compatibility between donor and patient.

What is HLA-B?

HLA-B is another Class I HLA marker. It is found on most nucleated cells and is important in immune recognition.

HLA-B presents protein pieces to CD8+ T cells to help the immune system recognise infected/abnormal cells.

HLA-B varies greatly meaning there are many variations between individuals. This means it is an important marker to consider when finding a donor.

Important points regarding HLA-B:

  • Class I HLA antigen.

  • Passed down from both parents.

  • Helps regulate the immune response.

  • HLA-B markers are tested during HLA matching for BMT.

  • Mismatch may increase risk of certain transplant complications.

What is HLA-DR?

HLA-DR is a Class II HLA marker. Unlike HLA-A and HLA-B it is mainly expressed on special immune cells including B lymphocytes, macrophage and dendritic cells.

HLA-DR helps the immune system recognise foreign substances by presenting protein pieces to CD4+ T cells.

HLA-DR plays an important role in immune responses and compatibility.

Important points regarding HLA-DR:

  • Class II HLA marker.

  • Mainly expressed on antigen presenting cells.

  • Helps activate CD4+ T cells.

  • Important marker during donor matching for BMT.

  • HLA-DR may affect risk of immune related transplant complications due to differences between donor and recipient.

Difference between HLA-A, HLA-B and HLA-DR 

All are Human Leukocyte Antigen markers but have different roles within the immune system.

Feature

HLA-A

HLA-B

HLA-DR

HLA class

Class I

Class I

Class II

Main location

Most nucleated cells

Most nucleated cells

Mainly antigen-presenting cells

Immune function

Presents antigens to CD8+ T cells

Presents antigens to CD8+ T cells

Presents antigens to CD4+ T cells

Inheritance

From both parents

From both parents

From both parents

Role in BMT

Donor matching

Donor matching

Donor matching

Importance

Helps identify cellular abnormalities

Important for immune compatibility

Helps regulate immune responses

 

HLA-A and HLA-B help the immune system recognise abnormal/infected cells whereas HLA-DR helps coordinate immune responses by activating CD4+ T cells.

They ALL play an important role in finding a compatible donor for BMT.

Why is HLA matching important prior to Bone Marrow Transplant?

HLA matching is one of the most important factors to consider prior to an allogeneic BMT.

During BMT stem cells will be given to the patient via the bloodstream. The donor immune cells need to be compatible with the recipient to reduce the risk of immune related complications.

HLA matching helps the doctor:

  • Find a suitable stem cell donor.

  • Reduce risk of Graft Versus Host Disease.

  • Reduce risk of graft rejection.

  • Increase chances of successful engraftment.

  • Plan suitable transplant protocol.

  • Find out if a sibling or family member may be a suitable donor.

For many standard allogeneic transplants HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 are tested. This is commonly referred to as high resolution 10/10 matching.

However the level of matching needed may vary depending on transplant type, donor availability and patient medical condition.

Sometimes a partially matched/haploidentical donor may be considered.

HLA Matching vs Blood Group Matching

HLA matching and Blood Group Matching are different tests.

Blood Group Matching tells you if the patient has blood group A, B, AB or O. It will also tell you if they are Rh positive or negative.

HLA typing will tell you what Human Leukocyte Antigens the patient has.

Differences include:

Feature

Blood Group Matching

HLA Matching

Purpose

Identifies blood group compatibility

Assesses immune compatibility

Main markers

ABO and Rh

HLA-A, HLA-B, HLA-C, HLA-DR and others

Used for

Blood transfusions and transplant planning

Stem cell donor selection

Testing

Blood group test

HLA typing

Importance in BMT

ABO compatibility is considered

Essential for donor compatibility assessment

 

Whilst a Bone Marrow donor may not have the same blood group as the patient HLA matching is an important factor when finding a suitable donor.

How is HLA Typing Performed?

HLA typing is usually performed using a blood sample. Sometimes a cheek swab will be used.

The laboratory will analyse the genetic material of the patient to find what HLA markers they have.

It usually involves:

Sample collection

A sample will be taken from the patient and potential donor. Some labs may use a cheek swab.

DNA extraction

The DNA will be extracted from the sample.

HLA testing

Molecular techniques will be used to find the HLA markers. Examples include PCR and NGS.

HLA typing

The lab will identify what HLA types the patient has. This includes HLA-A, HLA-B, HLA-C, HLA-DRB1 and other markers.

Donor comparison

The HLA profile will be compared between the patient and potential donor.

Specialist review

The BMT specialist will look at the results to decide if the donor is suitable.

How much does HLA matching cost in India?

The cost of HLA matching will depend on how many markers are being tested, the method used, the type of lab and if high resolution testing is required.

The cost may also vary if multiple potential donors need to be tested.

Type of HLA Test

Approximate Cost (USD)

Approximate Cost (NGN)

Basic HLA Typing

$100–$200

₦134,500–₦269,000

HLA-A, HLA-B and HLA-DR Typing

$150–$300

₦201,750–₦403,500

High-Resolution HLA Typing

$200–$500

₦269,000–₦672,500

Extended HLA Typing

$300–$700

₦403,500–₦941,500

 

HLA typing for Nigerian patients wanting a Bone Marrow Transplant in India

Nigerian patients can start the HLA typing process prior to travelling.

HLA typing can be done through a hospital or specialist lab in Nigeria. Depending on availability.

Alternatively it can be coordinated through a BMT hospital in India.

Typically:

Medical report

The patient should provide information on their diagnosis, medical history, previous treatment and any relevant blood investigations.

Potential donors

The patient may provide information on potential donors (such as siblings).

HLA typing

The hospital may advise HLA typing for the patient and potential donors. The lab should use the correct methods for testing and provide HLA results in a format the transplant team can understand.

HLA comparison

The specialist will look at the HLA profile to see if they match.

Donor assessment

If a potential donor is identified then further medical investigations will be performed to see if they are a suitable donor.

Planning

Once donor assessment has been performed and the patient has been assessed, the specialist can advise on the best option for transplant.

HLA typing Can Help Nigerian patients get started on finding a suitable donor for their BMT. However the final decision on donor choice and transplant should be made by the treating transplant team.

What if there is no Fully Matched HLA donor?

Not ALL patients will have a fully matched sibling donor. However this doesn’t necessarily mean that a BMT isn’t possible.

Depending on the patient’s condition and transplant requirements alternative donors may be considered.

These may include:

Haploidentical donor

A partially matched donor from the family. This could be a parent, child or sibling. They will have around half of the same HLA markers.

Matched unrelated donor

A suitable donor may be found from an unrelated donor register. The transplant team will look at the HLA profile.

Cord blood transplant

In some cases donated umbilical cord blood may be considered.

Autologous transplant

An autologous transplant uses the patient’s own stem cells so HLA donor matching isn’t required.

This will depend on the patient’s diagnosis, medical condition and what transplant options are available at the hospital.

Can siblings have different HLA types?

Yes. Siblings can have different HLA profiles. Each child will receive one HLA haplotype from each parent.

Full siblings will have around:

  • 25% chance of being fully HLA matched.

  • 50% chance of being haploidentical.

  • 25% chance of not receiving the same haplotypes from either parent.

These are general probabilities. HLA typing should be performed to see what compatibility there is between siblings.

This is especially important for Nigerian families looking to have a BMT for inherited blood disorders such as sickle cell and thalassemia.

Best hospitals for HLA typing and Bone Marrow Transplant in India

There are many hospitals in India that offer specialist Haematology and BMT services. Nigerian patients should look to choose a hospital based on their experience of BMT, HLA typing, donor assessment and post-transplant care.

Some hospitals to consider include:

FMRI, Gurugram

Fortis Memorial Research Institute offers specialist Haematology and BMT services. Patients can receive specialist consultations, BMT assessment, donor assessment and post-transplant monitoring.

They have experience treating blood disorders including sickle cell, thalassemia and leukaemia.

Medanta – The Medicity, Gurugram

Medanta offers specialist Haematology and BMT services. Patients can receive multidisciplinary care, investigations, donor assessment and treatment planning for various blood disorders and cancers.

Max Hospital, Saket

Max Super Speciality Hospital offers specialist Haematology and oncology services including BMT programmes. Patients can receive specialist consultations for BMT assessment, donor compatibility and treatment planning.

The best hospital will depend on your diagnosis, transplant requirements, donor availability and what your specialist recommends. Check with the hospital to see if HLA typing is available.

How GetWellGo Can Help with HLA typing for Nigerian patients

There are several steps involved in getting HLA typing and BMT done in another country. GetWellGo Can Help Nigerian patients by:

Medical report review

We Can Help organise a review of your medical reports with the correct Haematology or BMT specialist in India.

Finding the right hospital

We can help you find the right hospital to perform BMT based on your diagnosis and treatment requirements.

Virtual consultations

If you are in Nigeria we Can Help organise virtual consultations with Indian BMT specialists.

HLA typing

We Can Help organise HLA typing for patients and potential donors using the recommended lab from the hospital.

Treatment cost estimates

We can help you get an initial estimate for HLA typing, donor assessment and BMT treatment.

Medical visa support

If you need to travel to India for further investigations/treatment we Can Help organise the invitation letter from the hospital and relevant medical visa documents.

Transport and accommodation

We can help with airport transfers, accommodation near the hospital, local transport and organising appointments. We aim to make HLA typing easier for Nigerian patients and organising BMT in India.

Conclusion

HLA-A, HLA-B and HLA-DR are important markers to look at when finding a compatible donor for BMT. HLA-A and HLA-B are class I markers whilst HLA-DR is class II. When combined with other HLA markers they help the doctor find a compatible donor.

HLA typing can be an important first step for Nigerian patients wanting a BMT in India. The cost of HLA matching in India will depend on the method, number of markers and lab. GetWellGo Can Help Nigerian patients organise specialist consultations, HLA typing, donor assessment and BMT.

FAQs

  • What is the main difference between HLA-A, HLA-B and HLA-DR?

HLA-A and HLA-B are class I markers that present antigens to CD8+ T cells. HLA-DR is a class II marker that presents antigens to CD4+ T cells. All are important in immune function and BMT compatibility.

  • Why are HLA-A, HLA-B and HLA-DR tested prior to BMT?

These markers help the doctor compare the patient's HLA profile with a potential donor. This will reduce the risk of complications during transplant such as graft versus host disease and graft rejection.

  • How much does HLA matching cost in India?

The cost of HLA matching can range from around $100 to $700+. This will depend on how many markers are being tested, the method and lab. High resolution and extended HLA typing may cost more.

  • What is HLA typing for Nigerian patients?

HLA typing for Nigerian patients involves Testing

The patient’s HLA markers.can be organised in Nigeria or through the hospital lab in India.

  • Is HLA-A more important than HLA-B and HLA-DR?

No. All markers are important when finding a compatible donor. Multiple markers are looked at.

  • Can siblings have different HLA types?

Yes. Siblings will have different combinations of HLA markers. Full siblings have around a 25% chance of being fully HLA matched, 50% chance of being haploidentical and 25% chance of not having any complete haplotypes from either parent.

  • Does the donor need to have the same blood group?

No. Whilst the donor may not have the same blood group as the patient HLA compatibility is an important factor when finding a suitable donor. ABO compatibility will also be considered during transplant planning.

  • Can the patient have a BMT without a fully matched sibling?

Yes. Depending on the patient’s condition alternative donors may be considered. These may include haploidentical donors, matched unrelated donors or cord blood.

  • How long does HLA typing take in India?

This will depend on the lab, method and number of markers. Some tests may take several days. High resolution testing may take longer. The lab can give you an idea of how long it will take to get results.

  • Can Nigerian patients have HLA typing done prior to travelling to India?

Yes. If there is a suitable lab in Nigeria HLA typing can be organised. The transplant team in India should check that the lab is using the correct testing methods and that the reports are suitable for donor assessment.

  • Is HLA typing required for sickle cell BMT?

Yes. HLA typing is an important part of finding suitable donors for an allogeneic BMT for sickle cell. The transplant team will decide what testing needs to be performed and what donor options are available.

  • Can GetWellGo help organise HLA typing in India?

Yes. GetWellGo can help Nigerian patients organise HLA typing, virtual consultations, donor assessment, finding the right hospital and initial treatment estimates for BMT.

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