Prospective Measures of Adherence by Questionnaire, Low Immunosuppression and Graft Outcome in Kidney Transplantation.

BACKGROUND: Non-adherence with immunosuppressant medication (MNA) fosters development of de novo donor-specific antibodies (dnDSA), rejection, and graft failure (GF) in kidney transplant recipients (KTRs). However, there is no simple tool to assess MNA, prospectively. The goal was to monitor MNA and analyze its predictive value for dnDSA generation, acute rejection and GF. METHODS: We enrolled 301 KTRs in a multicentric French study. MNA was assessed prospectively at 3, 6, 12, and 24 months (M) post-KT, using the Morisky scale. We investigated the association between MNA and occurrence of dnDSA at year 2 post transplantation, using logistic regression models and the association between MNA and rejection or graft failure, using Cox multivariable models. RESULTS: The initial percentage of MNA patients was 17.7%, increasing to 34.6% at 24 months. Nineteen patients (8.4%) developed dnDSA 2 to 3 years after KT. After adjustment for recipient age, HLA sensitization, HLA mismatches, and maintenance treatment, MNA was associated neither with dnDSA occurrence, nor acute rejection. Only cyclosporine use and calcineurin inhibitor (CNI) withdrawal were strongly associated with dnDSA and rejection. With a median follow-up of 8.9 years, GF occurred in 87 patients (29.0%). After adjustment for recipient and donor age, CNI trough level, dnDSA, and rejection, MNA was not associated with GF. The only parameters associated with GF were dnDSA occurrence, and acute rejection. CONCLUSIONS: Prospective serial monitoring of MNA using the Morisky scale does not predict dnDSA occurrence, rejection or GF in KTRs. In contrast, cyclosporine and CNI withdrawal induce dnDSA and rejection, which lead to GF.

Evaluation of Next-Generation Sequencing and Crystal Digital PCR for Chimerism Monitoring of Post-Allogeneic Hematopoietic Stem Cell Transplantation.

Hematopoietic stem cell transplantation (HSCT) is a curative treatment for most hematologic diseases. To evaluate the level of donor engraftment, chimerism must be carefully monitored after HSCT. Short tandem repeats, quantitative PCR (qPCR), and, more recently, digital PCR (dPCR) are widely used to determine the proportions of donor and recipient cells after HSCT. The screening and quantification of chimerism have been evaluated by 2 new methods: a ready-to-use next-generation sequencing (NGS)-based method using the Devyser ChimerismNGS kit and an original combination of the Stilla crystal digital PCR (cdPCR) platform with 3-color multiplexing capacity using GenDX KMRtrack reagents. The genotyping of 4 HSCT pairs by cdPCR using 11 triplex mixes of the GenDX KMRtype kit was consistent at 98.8% with qPCR. Informative samples (n = 20) from 6 donor-recipient pairs and 1 external proficiency test demonstrated the reliability of the results (0.1% to 50%) for the 2 methods. The methods are also highly sensitive (0.1%) and accurate. The chimerism values of the 2 methods are correlated and concordant with those of the reference methods. In addition, the ADVYSER software (Devyser) is user-friendly and well adapted to chimerism monitoring. In conclusion, these 2 innovative methods are easy to perform and user-friendly in all molecular, hematology, and immunogenetic laboratories and allow the genotyping and monitoring of chimerism with high performance and sensitivity.

CD99 isoforms expression dictates T cell functional outcomes.

CD99, a unique integral membrane protein present on the surface of all human T cells, has previously been shown to regulate cell function and fate. In peripheral T cells, it triggers immediate activation of alpha4b1 integrin and cell arrest on inflamed vascular endothelium, whereas it mediates an apoptotic signal in double-positive thymocytes undergoing the selection process. Two isoforms of CD99 exist, a long form corresponding to the full-length protein and a short form harboring a deletion in the intracytoplasmic segment. Here, we show that while peripheral T cells display exclusive expression of the long form, double-positive thymocytes express both isoforms. Moreover, differential expression of these two CD99 molecules can lead to distinct functional outcomes. Expression of the long form in a CD99-deficient Jurkat T cell line is sufficient to promote CD99-induced cell adhesion, whereas coexpression of the two isoforms is required to trigger T-cell death. When coexpressed, the two proteins form covalent heterodimers, which locate within glycosphingolipidic rafts and induce sphingomyelin degradation. Cholesterol depletion experiments show that this localization is required for the induction of apoptosis. Thus, the surface expression pattern of CD99 isoforms determines T-cell functional outcomes.