Using single-cell analysis, a research team at St. Mary's Seoul Hospital has unveiled the cellular interactions, gene expression, and distinctive features of immune tolerance following kidney transplantation.

Kidney transplantation is considered the most ideal treatment for end-stage renal disease patients. However, patients need to take immunosuppressive drugs for their entire life to prevent the transplanted kidney from being attacked by the recipient's immune system, which has been identified as significant factors that shorten the lifespan of patients due to the risk of infections, malignancies, diabetes, hyperlipidemia, and nephrotoxicity,

For such reasons, it is crucial to identify the state of immune tolerance where no rejection occurs in kidney transplant patients, even with minimal or no immunosuppressive drug intake.

However, patients exhibiting immune tolerance are extremely rare, and research to accurately identify the immune cell and genomic characteristics of such patients is still ongoing.

To provide clues in accurately discovering such patients, a team, led by Professors Oh Eun-jee of the Department of Laboratory Medicine, and Chung Byung-ha, and Lee Han-bi of the Department of Renal Medicine, conducted a study using single-cell analysis on blood samples from four immune-tolerant patients.

The analysis revealed an increase in immature B cells and regulatory T cells, which are immune cells, in immune-tolerant patients.

Further analysis showed decreased expression of genes associated with immune responses in B cells of immune-tolerant patients.

Moreover, an increased expression of the CCR6 gene was observed in regulatory T cells of immune-tolerant patients, which is associated with the function of inhibiting effector T cells that induce rejection.

The team stressed that such findings indicate that gene expression changes favoring the suppression of immune responses occur in the immune cells of immune-tolerant patients.

Also, in addition to B cells and T cells, which have received attention in previous studies, the study also identified an increase in natural killer (NK) cells and natural killer T (NKT) cells in immune-tolerant patients, suggesting a potential contribution of innate immune cells to immune tolerance.

"While many studies have been conducted to identify genes involved in immune tolerance in kidney transplant patients, this is the first study to elucidate the correlations using single-cell analysis," Professor Oh said.

Professor Chung also expressed hope that the results will contribute to the selection of patients who can discontinue immunosuppressive drugs through blood tests of kidney transplant recipients in future clinical settings.

The results of this study were published online in the April issue of HLA Immune Response Genetics.