Cytotoxic T lymphocyte precursor frequency as a predictor of acute graft-versus-host disease in bone marrow transplantation from HLA-identical siblings

Evaluation of HistoCheck as a Predictor of Clinical Outcomes after Haploidentical Hematopoietic Stem Cell Transplantation

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is available for nearly all patients without matching HLA-related or -unrelated donors. There was not a valid evaluation system to predict the most proper donor. HistoCheck was based on the functional similarity of amino acids to estimate the allogenicity of HLA mismatches with a sequence similarity matching (SSM) score. We investigated whether HistoCheck could predict clinical outcomes in 500 patients with acute leukemia or myelodysplastic syndrome receiving haplo-HSCT. The total SSM score of the 5 loci (HLA-A, -B, -C, -DRB1, and -DQB1) had no association with clinical outcomes. HLA-C SSM score was significantly associated with transplant-related mortality (TRM) (hazard ratio [HR], .in691; 95% confidence interval [CI], .520 to .917; P = .011), disease-free survival (DFS) (HR, .714; 95% CI, .586 to .869; P = .001), and overall survival (OS) (HR, .711; 95% CI, .574 to .881; P = .002) by multivariate analysis. No significant associations were observed between other single-locus SSM score and clinical outcomes. In summary, our data demonstrate that a high HLA-C HistoCheck SSM score may lead to lower TRM and improved DFS and OS after haplo-HSCT and inclusion of HLA-C HistoCheck in donor selection criteria may need to be further confirmed in prospective studies.

Regulation of alloimmune responses (GvH reactions) in vitro by autologous donor bone marrow cell preparation used in clinical organ transplantation

BACKGROUND

Cadaver donor bone marrow cells (DBMC) are capable of a low-grade response to allogeneic stimulation in vitro, indicating their potential ability to cause graft versus host disease (GvHD). However, at this center, we have observed a lack of GvHD in kidney transplant recipients who received DBMC perioperatively. Therefore, we questioned whether an intrinsic immunoregulatory function of (subpopulations of) DBMC might play a role in this observation.

METHODS

In in vitro assays, DBMC was added to autologous splenic responder cells taking part in allogeneic mixed lymphocyte reaction (MLR) and cell-mediated lympholysis (CML) reactions.

RESULTS

When compared with autologous donor irradiated spleen cells as control modulators, DBMC significantly inhibited the CML, but to a much lesser extent than MLR, of autologous responding cells stimulated with allogeneic irradiated cells in a dose dependent manner. The down-regulation of CML responses was observed even in the presence of pharmacological concentrations FK506, mycophenolic acid, or cyclosporine-A. The inhibition could not be overcome by the addition of exogenous helper factors. Moreover, in contrast with findings previously reported from this laboratory of the in vitro inhibitory effect of DBMC on allogeneic responding cells in MLR and CML reactions to stimulating cells of the DBMC donor (allogeneic host versus graft inhibition), the following unique observations were made using DBMC inhibiting autologous reactions (GvH): (1) optimal restimulation of autologous responder cells in secondary cultures could not abrogate this inhibition; even activated responder cells could be inhibited by autologous DBMC, and (2) soluble factors were at least partially operative in this autologous (GvH) inhibition as indicated by experiments in transwells and by the CML inhibition caused by 50% supernatants from DBMC cultures.

CONCLUSION

These in vitro results indicate that DBMC treatment brings about a marked down-regulation of autologous immunocompetent cells in cytotoxicity reactions, partially at least through secreted soluble factor(s), (and in presence of immunosuppressive drugs in vivo) thereby preventing overt clinical GvHD.