Innovations 2022 in hematological biology

Véronique Deneys1, Antoine Buemi2*, Virginie Chapelle1, Tom Darius2*, Martine De Meyer2*, Arnaud Devresse2,3*, Yannick France2*, Valérie Dumont2, Thibaut Gervais1, Eric Goffin3*, Louise Guillaume, Nada Kanaan³*, Youssra Khaouch1, Catherine Lambert1*, Urs Published in the journal : February 2023 Category : Biologie Hématologique

Summary :

The year 2022 saw a gradual return to normal after the COVID-19 pandemic. This was an opportunity to optimize processes that had sometimes been undermined and to update procedures. It was also an occasion to take on new challenges: to consider acquiring new equipment for the coming years, to implement new techniques that are more sensitive, faster, and better adapted to the needs of prescribers.

In the Special Hematology Laboratory, and in particular in the specialized hemostasis sector, the automation of the ADAMTS13 protein assay was critical for the diagnosis and biological follow-up of patients with immune thrombotic thrombocytopenic purpura (iTTP). This uncommon condition can rapidly deteriorate if not diagnosed early and managed appropriately based on ADAMTS13 testing. This assay also allows identifying patients at risk of relapse who should receive preventive treatment.

The determination of erythrocyte blood groups is most often straightforward using serological techniques. However, in certain situations, it is necessary to use molecular biology techniques. The Immunohematology - Molecular Biology Laboratory has implemented a real-time PCR technique that allows for extensive erythrocyte genotyping and the detection of antigenic variants missed by serological techniques. This is an essential tool for determining blood groups in polytransfused patients and for selecting bags for individuals with a variant or deletion blood group.

It has been known for over 50 years that the HLA system plays a central role in human immunity and is at the same time one of the main obstacles to organ transplantation. The involvement of anti-HLA antibodies in early and late rejection is indisputable. In 2021, the Leuko-Platelet Immunology Laboratory has implemented a new test for a more specific identification of clinically relevant anti-HLA antibodies, which facilitates graft allocation. In 2022, the records of patients awaiting renal transplant who had anti-HLA antibodies were reviewed, and controls were performed on old sera using the new technique. This allowed the removal of "forbidden" antibody specificities in more than half of the patients, thereby increasing their chance of receiving a compatible graft. Six patients received a kidney graft carrying an HLA antigen previously listed as forbidden with the old technology and removed after revision. Currently, all these patients have displayed a functional graft without immunological complications. These results will be presented at the European Foundation for Immunogenetics (EFI) Congress in April 2023. Although transfusion is a common and beneficial therapeutic procedure for the patient, transfusion reactions can occur. The diagnosis of these reactions is sometimes confusing and difficult. The Hemovigilance Transfusion Sector has developed new decision-making algorithms based on the main symptoms presented by the patient and the blood component involved in the reaction. These algorithms are intended to guide towards a diagnosis and, in order to achieve this, to determine the controls and laboratory tests that must be carried out in each situation. These algorithms have been published in the journal of the Société Francophone de Transfusion Sanguine.

While there were already warning signs of a shortage in 2021, the supply situation for O-negative red blood cells worsened considerably in 2022. The Blood Bank, in consultation with the Medical Direction and the Transfusion Committee, had to deal with this by implementing various actions to try to stop the "hemorrhage". This is the subject of a specific procedure: implementation of very strict and closely monitored indicators, prioritization of transfusion indications, exclusive unitary distribution (outside of hemorrhagic situations), and medical decision to transfuse Rh-positive erythrocyte concentrates to Rh-negative recipients. Various very precise assessments of this situation are still underway and will soon be submitted for publication. Concerted action has been taken within the network hospitals and initiatives are also being taken at the national level.

Finally, the year 2022 also witnessed the publication of a new European directive and new EDQM (European Directorate for the Quality of Medicines) standards defining blood as a SoHO (Substance of Human Origin), similar to cells and tissues. For this reason, it was decided that the Blood Bank and the Erythrocyte Immunology Laboratory would join the Banking Department as of January 1, 2023.

Key words

ADAMTS13, iTTP, genotyping, blood groups, HLA, transplantation, immunization, transfusion reaction, O negative, shortage