Histocompatibility testing for solid organ transplantation

We provide services to support kidney, simultaneous pancreas-kidney (SPK), islet and liver transplantation.

• Human leukocyte antigen (HLA) typing is undertaken by Polymerase chain reaction (PCR) based assays.
• HLA antibody screening is undertaken by bead based technology used to semi quantitatively detect HLA Immunoglobulin G (IgG) antibodies.
• Crossmatching for living or deceased donor transplants is performed by flow cytometry.

Sample requirements

If you requre a copy of our Sample Requirements policy, please contact NSS.handi@nhs.scot

Kidney, kidney/pancreas and islet transplant patients

For initial testing:

• 5ml ethylenediaminetetraacetic acid (EDTA) for HLA typing
• 5ml clotted for HLA antibody screening

For confirmatory testing:

• 5ml EDTA for HLA typing
• 5ml clotted for HLA antibody screening

For testing while listed:

• 5ml clotted for HLA antibody screening every 3 months

For post transplant monitoring:

• 5ml clotted for HLA donor-specific antibody (DSA) screening

Liver patients

At time of transplant:

• 5ml clotted for HLA antibody screening

Local deceased donor

For HLA typing:

• 40ml EDTA for HLA typing

Living donors

For HLA typing:

• 5ml EDTA for HLA typing

Crossmatching requirements

Virtual crossmatch

For donors:

• 5ml EDTA for HLA typing

For patients:

• 5ml clotted for HLA antibody screening

Wet crossmatch

For donor:

• 20ml EDTA or tissues from deceased donor

For recipients:

• 5ml clotted for HLA antibody screening
• 20ml EDTA for autoXM

How to contact our lab for histocompatibility testing enquiries.

Virtual crossmatch eligibility

A virtual crossmatch (vXM) eliminates the need for a prospective crossmatch and benefits the patient by reducing the cold ischaemic time of the graft.

Patients may be eligible for a vXM if:

• they have not received a previous transplant
• they have been shown to be consistently negative for HLA antibodies by Luminex testing or have a consistent HLA antibody profile
• they have sent a recent (within the last 3 months) sample to the laboratory and have had no sensitising events since the last sample was tested, for example transfusions or failed pregnancies
• sensitised, previously transplanted patients may still be eligible for a vXM where a day of transplant sample has been tested for HLA antibodies using SAB testing

In all cases, donor and recipient samples must be sent to the lab.

Reporting of crossmatch results

• Results of the compatibility testing for deceased donor transplants will be sent to the recipient transplant co-ordinator as soon as they are available.
• vXM reports will also be sent prior to transplant where applicable.
• Reports will show the crossmatch results for the CDC and flow crossmatch, where applicable.
• A comment will be included to interpret the data generated.
• Any unexpected positive crossmatch result will be discussed between the on-call healthcare scientist and clinical scientist, who will also be available to discuss any findings with the clinical team.

You should be aware that, as the data generated by the flow cytometer is numerical and semi-quantitative, there is an inherent uncertainty (or variability) in the data generated.