Naslov
HLA CROSSMATCH IN PATIENT ON RITUXIMAB THERAPY

Autori
Maskalan, Marija ; Burek Kamenarić, Marija ; Jukić, Lucija ; Štingl Janković, Katarina ; Martinez, Natalija ; Grubić, Zorana ; Žunec, Renata

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstract Book HDNDT / - , 2022, 23-23

Skup
9. Transplantacijska škola

Mjesto i datum
Metković, Hrvatska, 22-25.09.2022

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
HLA ; crossmatch ; rituximab

Sažetak
Introduction Rituximab is a genetically engineered recombinant chimeric monoclonal antibody directed against CD20 antigen expressed on the surface of B cells. It can activate the complement-mediated cytotoxicity and in that way reduce B cells in the peripheral blood. It is used as a treatment of several autoimmune disorders and B-cell malignancies but also to control and prevent humoral rejection in solid organ transplantation (SOT). However, rituximab when present in the sera of patients awaiting SOT causes false positive crossmatch (CM) due to the structural homology of Fc receptors on activated T-cells. This could be a possible explanation of the same and provide insight into a novel mechanism of action of rituximab. Case report A 49-year-old male patient with ANCA-vasculitis and chronic kidney insufficiency was assessed for kidney transplantation from a family member in 2018 but was not transplanted due to the clinical condition of the potential donor. Luminex Single Antigen Beads (SAB) testing was performed and turned to be positive for HLA-B73 with virtual panel reactive antibodies (vPRA) 1%. The patient was registered on Eurotransplant waiting list in April 2021 and got his first kidney offer in April 2022 but the acceptance had to be withdrawn due to the unexpected positive CM result. Positive CM was unexplainable by the previous HLA and non-HLA antibody detection and identification tests. Clinical data revealed that patient started rituximab therapy in April 2019 and received total of five doses, the last one in November 2021. In the period from February to June 2022 patient had four more unexplainable positive CMs. The CM tests were performed with serum samples drawn in December 2021 and March 2022, i.e. one and four months after the rituximab therapy. In July 2022, patient received a cadaveric kidney offer, Luminex SAB testing confirmed the absence of DSAs and negative CM was obtained with serum samples drawn in June 2022 and at the day of transplantation i.e. with samples drawn 8 months after the last rituximab dose. Conclusion In the light of the growing use of rituximab in various medical conditions, it is vital to know the clinical and drug history of the recipient before interpretation of any immunological test. The SAB assay is a valuable technique in this setting as the presence of rituximab does not influence it, while CM results are dependent on the time frame of the last rituximab dose.

Izvorni jezik
Engleski

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