Probir antitijela non-HLA – prvi rezultati

Marija Burek Kamenarić, Lucija Jukić, Renata Žunec

Cilj: Važnost i uloga antitijela usmjerenih protiv humanih leukocitnih antigena (HLA) u reakcijama odbacivanja posredovanih antitijelima nakon transplantacije solidnih organa danas je jasno dokazana. Smatra se da su i antitijela usmjerena na antigene koji nisu dio sustava HLA, tzv. antitijela non-HLA, također povezana s humoralnim odbacivanjem te da mogu utjecati na preživljenje presatka. Prisutnost antitijela non-HLA dodatno ukazuje na bolesnike s povećanim imunološkim rizikom prije i nakon transplantacije organa. Cilj rada bio je odrediti prisutnost antitijela non-HLA u skupinama bolesnika prije i nakon transplantacije bubrega, odrediti njihovu učestalost pojavljivanja validiranim testovima probira te verificirati analizu rezultata. Ispitanici i metode: Analiza prisutnosti antitijela non-HLA provedena je u 17 visoko HLA-senzibiliziranih bolesnika na listi čekanja za transplantaciju bubrega (skupina pre-tx) i u 10 bolesnika s transplantiranim bubregom (skupina post-tx) čiji nalazi biopsija ukazuju na humoralno odbacivanje, a bez dokazanih prisutnih donor-specifičnih antitijela HLA (DSA). Za određivanje antitijela non-HLA korišten je test temeljen na tehnologiji Luminex koji omogućuje izravnu simultanu detekciju antitijela IgG protiv 60 različitih antigena non-HLA. Rezultati: Prisutnost antitijela non-HLA najmanje jedne specifičnosti dokazana je u 16/17 (94,1%) primatelja pre-tx skupine te u 7/10 (77,0%) primatelja post-tx skupine. Vrijednosti intenziteta fluorescencije pozitivnih reakcija bile su statistički značajno više u pre-tx skupini u usporedbi s post-tx skupinom. Broj specifičnosti antitijela non-HLA određenih po pojedinom primatelju bio je veći u pre-tx skupini. Zaključak: Test omogućuje vrlo osjetljivo dokazivanje prisutnosti i specifičnosti antitijela non-HLA. Prisutnost antitijela non-HLA visoka je u obje ispitivane skupine, a broj specifičnosti i intenzitet pozitivnih reakcija značajno je veći u visoko HLA-senzibiliziranih primatelja. Biopsijom dokazano humoralno odbacivanje bez prisutnih HLA DSA može biti povezano s antitijelima non-HLA u post-tx skupini.

Objective: The importance and role of antibodies directed against human leukocyte antigens (HLA) in antibody-mediated rejection (AMR) reactions after solid organ transplantation has been clearly demonstrated. Antibodies against non-HLA antigens (non-HLA antibodies) are also thought to be associated with humoral rejection and may affect graft survival. The presence of non-HLA antibodies additionally indicates an increased immunological risk before and after organ transplantation. The aim of the work was determination of non-HLA antibodies in groups of patients before and after kidney transplantation using validated screening tests for non- HLA antibodies and, based on results analysis determine the frequency of non-HLA antibodies occurrence. Subjects and Methods: We tested one of the two currently available non-HLA antibody assays based on Luminex platform which allows the direct simultaneous detection of IgG antibodies to 60 non-HLA auto-antigens. The tested cohort consisted of 17 HLA highly sensitized recipients on the kidney waiting list (pre-tx group) and 10 kidney transplant recipients (post-tx group) with biopsies showing evidence of AMR in the absence of detectable HLA donor-specific antibodies (DSA). Results: The presence of at least one of non-HLA antibody was detected in
16/17 (94.1%) pre-tx group recipients while in post-tx group non-HLA antibody was detected in 7/10 (77.0%) recipients. The fluorescence intensity for positive reactions was significantly higher in pre-tx group compared to post-tx group. The number of different non-HLA specificities detected per recipient was also much higher in pretx group. Conclusion: The assay enabled highly sensitive detection and characterization of non-HLA antibodies. The presence of non-HLA antibodies is high in both investigated groups, and the number of specificities and intensity of positive reactions were significantly higher in HLA highly sensitized recipients. Biopsy proven AMR without detected HLA DSA can be associated with the presence of non-HLA antibodies in the post-tx group.