Specialisms | Histocompatibility & Immunogenetics

What is Histocompatibility and Immunogenetics (H&I)?

That’s a question I’m only just getting to grips with, having started my training last September. On the most basic level, it’s easiest to say that it’s matching people for transplants, and although that is the majority of the work that scientists in this specialism do, they also use their skills to support clinicians in other areas of patient care. The STP is one of the main training routes for clinical scientists in this field, so if you’re considering H&I, then the STP is one of the best ways to get into it.

The primary focus of H&I is concerned with looking at an area of the genome known as human leukocyte antigen (HLA) in humans. HLA genes are important as these are how the immune system distinguishes the body’s own cells from foreign material and pathogens. Therefore, they are extremely important when looking at transplantation – if the body recognises the transplant as foreign material then it could be rejected!

Depending on the type of transplant, H&I laboratories perform different tests to determine whether an organ is suitable for transplantation. These include:

  • HLA Typing – to find out the HLA alleles of the recipient and donor to ensure a suitable match can be found. This can be done by:
    • Next-generation sequencing
    • Real-time PCR
  • Antibody Screening – this detects any antibodies that could prevent patients from receiving organs with certain HLA types (again ensuring that organs are allocated to those with the best match). After transplant, monitoring antibody levels gives an indication of how the transplanted organ is doing, and whether the patient has developed any new antibodies that are specific to the donor organ, indicating potential for rejection. Current methods for this include:
    • Complement-dependent cytotoxicity
    • Flow cytometry
    • Luminex
  • Crossmatching – helps determine whether a donor and recipient are compatible, and the risk of hyperacute rejection upon transplant. Can be done physically, or predicted virtually using antibody screening data.

Some H&I laboratories also provide HLA typing and antibody screening services for patients with platelet refractoriness following transfusion.

The STP prepares you to understand the principles behind why these tests are performed, to actually be able to perform these, as well as to interpret the results and guide the decision on whether a transplant is suitable to go ahead.

Scientists working in H&I also use their skills to aid in the diagnosis of conditions such as coeliac disease and ankylosing spondylitis due to their link to specific HLA alleles. If doctors suspect that a patient has one of these conditions, they will send a blood sample to an H&I laboratory, where it will be tested to see if the patient has the allele associated with the disease. If the patient does have the allele, along with other symptoms, then this can aid the doctors in diagnosing their conditions and getting the treatment they need.

HLA alleles can also play a role in drug hypersensitivity reactions, and by screening for the associated alleles, scientists can help patients get the best treatment, and therefore gain a better quality of life.

Even if your laboratory does not perform some of the processes described, you will be able to visit other laboratories that do perform them during your training, so that by the end of the training, you have the knowledge and skillset to work as a clinical scientist in any of the H&I laboratories around the country.

Hopefully, this has managed to give an overview of what scientists working in H&I get up to. This is a lab-based specialism, and although we don’t get to meet the patients, there is a definite satisfaction in finding out that a patient who has kept popping up has received a transplant, as you have played a part in helping them to achieve that!

As a final word, if you’re planning to apply this year, or you’ve applied before and are wondering whether it’s worth it, I’d say keep trying. I applied three times before getting in – you never know, this year could be your year!

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