Kroemer et al at Georgetown-Medstar Transplant Institute in Washington, DC, recently reported the first ever intestine transplant recipient to show operational tolerance or a stable rejection-free status without immunosuppression. Phenotypic analysis of peripheral blood lymphocytes revealed an increase in circulating T-regulatory cells. This patient also demonstrated immunological quiescence toward donor alloantigens. Immunological reactivity toward other antigens was preserved. These functional tests were performed at Plexision.

Sanchez-Fueyo et al at King’s College Hospital in London, UK, assessed the safety of infusing two doses of ex-vivo-expanded T-regulatory cells (Tregs) to liver transplant recipients. Treg infusions can provide anti-rejection effect with fewer side effects than small molecule immunosuppressants, and reduce the need for these immunosuppressants. No adverse events were reported in this study. Immunophenotyping revealed an increase in circulating Tregs for up to a month after infusion following the higher dose infusion of 3-4.5 million Tregs/kg.

Soltys and Fox et al transplanted human hepatocytes in two patients with urea cycle defects. Retrospective immune monitoring was performed to assess the adequacy of immunosuppression. Early graft loss in both cases was accompanied by an increase in rejection-risk measured with donor-specific CD154+T-cytotoxic memory cells. Lymphocyte depleting induction immunosuppression was used in the next patient who received hepatocyte transplantation for phenylketonuria. Biochemical improvement of disease markers was confirmed in supervised follow-up for several months.