ABO-incompatible kidney transplantation with high isoagglutinin titres: practice pattern and problem solving: a German multi-centre survey.

INTRODUCTION

ABO-incompatible kidney transplantation (ABOi-KT) expands the donor pool, yet baseline anti-ABO isoagglutinin titres ≥ 1:512 remain challenging and practice is highly variable. We surveyed the German transplant centres to capture current management of very high-titre ABOi candidates and centre responses to insufficient titre decline.

METHODS

Thirty-six centres were invited to complete an anonymised 19-item web-based questionnaire (January-March 2025) on (i) centre activity, (ii) isoagglutinin testing and isoagglutinin titre limits (iii) desensitisation protocol, (iv) ABO abort criteria and (v) escalation & re-attempt strategies. Data are reported descriptively.

RESULTS

Of 36 eligible programmes, 27 (75%) responded. Thirteen (48%) accept any isoagglutinin titre; the rest cap at 1:512 (15%), 1:1024 (26%) or 1:2048 (11%). Centres without a cap reported greater 5-year ABOi experience (median 20 vs 9 cases). IgG isoagglutinin titres are monitored in 26/27 centres, IgM in 18/27. All centres use rituximab, usually 4 weeks pre-transplant. Antigen-specific immunoadsorption (IA) is the principal antibody-removal method in 88%, while 54% also employ plasma exchange (PLEX). In cases of insufficient titre decline, different strategies are employed. Desensitisation is halted mainly for refractory isoagglutinin titres or serious complications; 67% of programmes would re-attempt after 3-6 months, typically with intensified apheresis and/or additional B-cell depletion.

DISCUSSION: German centres display marked protocol heterogeneity, but all accept very high titres, relying on rituximab plus IA. Greater experience correlates with abandonment of fixed cut-offs. Harmonised isoagglutinin titre assays, evidence-based futility criteria and multicentre registries are needed to optimise high-titre ABOi-KT.