Measuring the resting naive sub-population of T-regulatory cells improves prediction of suppressive function of clinical grade T-regulatory products

Enumerating regulatory T cells in cryopreserved umbilical cord blood samples using FOXP3 methylation specific quantitative PCR

BACKGROUND

Allogeneic haematopoietic cell transplantation (HCT) is a curative therapy for severe haematological disorders. However, it carries significant risk of morbidity and mortality. To improve patient outcomes, better graft selection strategies are needed, incorporating HLA matching with clinically important graft characteristics. Studies have shown that the cellular content of HCT grafts, specifically higher ratios of T regulatory (Tregs)/T cells, are important factors influencing outcomes when using adult peripheral blood mobilised grafts. So far, no equivalent study exists in umbilical cord blood (CB) transplantation due to the limitations of cryopreserved CB samples.

STUDY DESIGN AND METHODS

To establish the most robust and efficient way to measure the Treg content of previously cryopreserved CB units, we compared the enumeration of Treg and CD3+ cells using flow cytometry and an epigenetic, DNA-based methodology. The two methods were assessed for their agreement, consistency and susceptibility to error when enumerating Treg and CD3+ cell numbers in both fresh and cryopreserved CB samples.

RESULTS

Epigenetic enumeration gave consistent and comparable results in both fresh and frozen CB samples. By contrast, assessment of Tregs and CD3+ cells by flow cytometry was only possible in fresh samples due to significant cell death following cryopreservation and thawing.

CONCLUSION

Epigenetic assessment offers significant advantages over flow cytometry for analysing cryopreserved CB; similar cell numbers were observed both in fresh and frozen samples. Furthermore, multiple epigenetic assessments can be performed from DNA extracted from small cryopreserved CB segments; often the only CB sample available for clinical studies.

Different phenotypes of CD4+CD25+Foxp3+ regulatory T cells in recipients post liver transplantation

CD4⁺ regulatory T cells (Tregs) play an important role in inducing immune tolerance in organ transplantation, which can be divided into CD45RA⁺Tregs (resting Tregs, rTregs) and CD45RO⁺Tregs (activated Tregs, aTregs). Currently, the expressions and phenotypic changes of Tregs in recipients after liver transplantation (LT) is unknown. We therefore investigated the expression and transformation of rTregs and aTregs in 83 cases of recipients with normal status post-LT. The percentages of CD45RA, CD45RO, CD31 in CD4⁺Tregs were detected by flow cytometry and the effective factors were analyzed. In LT recipients, the percentage of CD45RO⁺Tregs in CD4⁺Tregs was higher than that of CD45RA⁺Tregs. There was significant difference in the ratio of positive Foxp3 between CD45RA⁺Tregs and CD45RO⁺Tregs. Percentage of CD45RA⁺Tregs was higher in pediatric group than that in adult group, whereas percentage of CD45RO⁺Tregs was lower in the pediatric group. However, it was different only in CD45RO⁺Tregs in various survival periods post-LT. In conclusion, Tregs pool in human was heterogeneous post-LT and contained different subsets in phenotypes. Upon stimulation by donor graft, percentages of CD4⁺Tregs and CD45RO⁺Tregs were increased post-LT and most of rTregs was transformed into aTregs in peripheral blood, and rTregs and aTregs were both related to recipients' ages.