New Method to Avoid Kidney Transplant Rejection Using White Blood Cells

A group of white blood cells plays an important role in controlling replication of the BK polyomavirus (BKPyV) that causes premature kidney transplant failure.

Highlights

BK polyomavirus (BKPyV) is the most common cause of premature transplantation failure, following kidney transplant.
Current treatments include screening for the virus in the blood and, if positive, aims to reduce immunosuppression.
A group of lymphocytes, BK virus-specific CD8 killer T lymphocytes, have been found to be effective in bringing the BK polyomavirus replication under control, thus avoiding transplant rejection.

A group of white blood cells has been found to play an important role in bringing the replication of the harmful virus, BK polyomavirus (BKPyV), under control after kidney transplantations.

The findings by a research group at the Department of Biomedicine at the University of Basel and University Hospital Basel could contribute to:

improving control of immunosuppression
avoiding transplant rejection
developing relevant vaccines

The harmful BK polyomavirus was first identified as a cause of early transplantation failure more than ten years ago at the University Hospital Basel.

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‘The group of lymphocytes identified could be harnessed for improved control of the reduction in immunosuppression, avoiding transplant rejection and contributing towards the development of vaccines.’

Infection by BK polyomavirus (BKPyV) occurs commonly following kidney transplant. It causes premature kidney transplant failure in about 1-15% of the patients. This leads to deterioration in kidney function or eventually the loss of the new kidney.

Currently, there is no effective treatment for BK polyomavirus infection.

There is a shortage of antivirals and the treatments rely solely on the blood levels of viral load, so that appropriate decisions can be made regarding the use of immunosuppressive medication to prevent a transplant rejection.

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Role of Lymphocytes

The researchers investigated the blood of 96 patients immediately after a kidney transplant, and then six and twelve months afterwards.

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Among the patients, 28 had tested positive for BK polyomavirus and the remaining 68 served as non-viremic controls.

The results showed that in patients who were able to bring the virus under control, certain white blood cells, BK virus-specific CD8 killer T lymphocytes, were significantly increased.

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These blood cells were detectable in patients with different tissue types and could be propagated in cell cultures.

"Our results open up new opportunities for improved control of the reduction in immunosuppression and contribute to the development of vaccines and adoptive T-cell therapy," says Professor Hans H. Hirsch.

Céline Leboeuf and Sabrina Wilk, from Professor Hans H. Hirsch's research group, reported the results of a collaboration between Swiss transplant centers in the latest issue of the American Journal of Transplantation.

Reference

Céline Leboeuf et al. BK polyomavirus-specific 9mer CD8 T-cell responses correlate with clearance of BK viremia in kidney transplant recipients: First report from the Swiss Transplant Cohort Study (STCS). American Journal of Transplantation; (2017) DOI: 10.1111/ajt.14282