Laboratory of Transplant Medicine
The Laboratory of Transplant Medicine was established on January 1, 2025. Its mission is to supervise laboratory examinations performed at the Institute of Hematology and Blood Transfusion for hematopoietic stem cell transplantation (HSCT)
The aim of the laboratory is to coordinate individual examinations to ensure maximum benefit for transplanted patients.
Representatives of the laboratory actively participate in clinical seminars focused on the selection of suitable hematopoietic stem cell donors for specific patients.
The Laboratory of Transplant Medicine consists of the Department of HLA, the Department of Cell Chimerism, and the Laboratory of HLA serology.
The Department of HLA performs specialized immunogenetic tests of patients indicated for hematopoietic stem cell transplantation, their relatives, and selected unrelated donors to find the most suitable donor for transplantation.
When examining patients and searching for suitable donors, the human immune system – HLA (Human Leukocyte Antigens) – is tested at a high-resolution level using a highly accurate method of massively parallel sequencing.
The most suitable donor from an immunological point of view is an HLA-matched sibling. If the patient does not have a match sibling, potentially suitable donors are selected from registries of unrelated donors based on their HLA types, and they are retested at the department to determine their degree of compatibility with the patient. The goal is to find a donor with the highest possible degree of HLA compatibility. Another option is so-called haploidentical transplantation, where the patient shares only half of the HLA markers (one haplotype) with the donor. For this type of transplantation, donors are sought among immediate family members (siblings, parents, and children of the patient). In exceptional cases, more distant relatives can also be considered.
The Department of Cell Chimerism conducts DNA analysis of the patient before transplantation and of the selected donor. The aim is to identify differences in non-coding DNA sequences that will enable the differentiation of both genetic profiles in the mixture after transplantation and the subsequent quantification of their representation.
The main purpose of cell chimerism testing is long-term post-transplant monitoring, particularly tracking graft engraftment dynamics and enabling early detection of the return of the recipient haematopoiesis, which may indicate a risk of haematological malignancy relapse. Chimerism testing is routinely performed on peripheral blood or bone marrow. If necessary, it is also available for specific cell subpopulations of peripheral blood, allowing for more targeted graft monitoring.
The Department of Cell Chimerism organizes external proficiency testing annually.
The Laboratory of HLA serology primarily focuses on the detection and identification of HLA class I and II antibodies. These antibodies are analysed using highly sensitive solid-phase assays on multiplex immunoanalysers (Luminex-type instruments). Screening and identification of HLA antibodies via solid-phase testing are indicated for all patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT), regardless of whether the potential donor is related or unrelated. This testing supports the selection of the most suitable donor and contributes to personalised transfusion therapies both before and after HSCT.
Scope of services:
Examinations performed prior to hematopoietic stem cell transplantation:
HLA genotyping of patients, relatives, and selected unrelated donors
(performed by the Department of HLA)
After transplantation is indicated, high-resolution HLA genotyping is performed on the patient at the HLA class I and II loci. The same HLA typing is performed on all siblings medically eligible to donate stem cells. Testing of selected unrelated and other related donors is performed using the same methods, based on agreement with transplant specialists.
Determination of HLA compatibility between donor and recipient
(performed by the Department of HLA)
Based on the HLA tests described above, the degree of compatibility between the patient and their donors is determined.
Screening and identification of HLA antibodies
(Performed by the Laboratory of HLA serology)
The purpose of this testing is to detect and, where applicable, determine the specificity of a patient's HLA antibodies directed against mismatched HLA antigens of a potential donor (donor-specific antibodies, DSA). Patients with DSA are at increased risk of graft rejection, delayed engraftment, and poorer transplant outcomes. Therefore, the presence of HLA antibodies in the patient is continuously monitored to support the selection of a donor whose HLA antigens are not targeted by the patient’s DSA. If no suitable donor lacking the targeted HLA antigens is available, a desensitisation strategy may be considered based on the patient's specific HLA antibody profile. This approach can lead to a reduction or even elimination of DSA from the patient’s circulation, thereby decreasing the risk of graft rejection and other post-transplant complications.
Solid-phase screening assays (Luminex) using affinity-purified native and recombinant HLA antigens are used to detect the presence of HLA class I and class II antibodies, including those directed against HLA-DP antigens. This testing is particularly important for patients with unrelated registry donors matched at 10/10 HLA loci, as mismatches may still occur at the DP locus. Screening results are further complemented by Luminex single antigen bead (SAB) assays, which enable precise identification and characterization of specific HLA class I and class II antibodies.
Lymphocytotoxic crossmatch
(Performed by the Laboratory of HLA serology)
The lymphocytotoxic crossmatch test evaluates the interaction between complement-activating HLA antibodies in a patient´s serum and mismatched HLA antigens expressed on donor lymphocytes. This test is performed for patients indicated for hematopoietic stem cell transplantation with a related potential donor, as well as prior to the administration of transfusion products (most commonly platelets), to minimise the risk of transfusion reactions and bleeding complications associated with platelet refractoriness.
Immunological risk stratification of individual donors
(Performed by the Laboratory of HLA serology in collaboration with the Department of HLA)
The patient's profile of individual HLA class I and class II antibody specificities is compared with the HLA genotypes of potential donors at the A, B, C, DRB1, DQB1, DQA1, and DPB1 loci, and, where indicated, at the DPA1, DRB3, DRB4, and DRB5 loci. Particular attention is given to the presence of donor-specific antibodies (DSA) directed against mismatched donor HLA antigens. When DSA are detected, additional testing is performed to identify complement-activating HLA antibodies (C3d component) using Luminex single antigen bead (SAB) assay. This comprehensive assessment enables a personalised approach to the management of desensitisation protocols in patients with DSA.
Tests performed after hematopoietic stem cell transplantation:
Cell chimerism testing after allogeneic HSCT
(performed by the Department of Cell Chimerism)
Cell chimerism testing is based on genotyping and quantification of variable polymorphisms, specifically short tandem repeats (STRs) and short deletions and insertions (indels), located in non-coding regions of DNA. These genetic markers enable the identification of individual cell populations within the sample and allow for precise quantification of their relative proportions.
Modern molecular biology methods are used to analyse cell chimerism, including polymerase chain reaction with fragment analysis, which enables the detection of minority cell populations with a sensitivity of up to 1%, and real-time PCR (qPCR), achieving a sensitivity of up to 0.035%. These technologies enable accurate and reliable monitoring of chimerism and provide important information for clinical decision-making in transplant care.
Detection of HLA-loss relapse
(performed by the Department of Cell Chimerism in cooperation with the Department of HLA)
When chimerism increases in non-HLA markers in patients following haploidentical transplantation, it is possible to examine whether there has been a loss of the patient's HLA-mismatched haplotype, known as HLA-loss relapse. This test is performed by quantifying patient-specific HLA markers using real-time PCR (provided by the Cell Chimerism Department). If the HLA marker is not available, it is possible to quantify patient-specific HLA using next-generation sequencing (provided by the HLA Department).
This test is essential for determining the subsequent treatment strategy. In the case of HLA-loss relapse, standard administration of donor T-lymphocytes is ineffective, requiring a different approach to treatment than in classic relapse.