The New England Journal of Medicine disclosed that three children who recently received kidneys from their haploidentical parents may never need immunosuppressive medicines.

The three children received their kidneys, as well as reduced-intensity conditioning and T-cell–depleted and CD19 B-cell–depleted hematopoietic bone marrow. The required medications including anti-thymocyte globulin (7.5 mg/kg), fludarabine (1 mg/kg/day for 4 days) and cyclophosphamide (1,200 mg/m2), then total-body irradiation (200 cGy) and rituximab (200 mg/m2) were administered to the patients to prepare for the HSCT (hematopoietic stem-cell transplantation).

The transplantation was done once donor myeloid and lymphoid chimerism following HSCT had been confirmed (at 5, 5.5, and 10 months for the individual patients). The patients were given intraoperative methylprednisolone and postoperative low-dose oral prednisone and tacrolimus in order to decrease reperfusion inflammation. Doses of these drugs were tapered down by day 30 and no further immunosuppression was required to be given.

The patients showed no clinical evidence of rejection. At 22 to 34 months after transplantation, renal function is normal. Two patients responded to further immunizations with a protective response, and the third was awaiting titer data at the time of publishing.

The researchers noticed that 1 year after kidney transplantation, peripheral blood mononuclear cells demonstrated functional tolerance to stimulator cells generated from their donor parent, and, thus, potentially unable to cause graft rejection even in the absence of immune suppression. However, in the presence of stimulator cells obtained from their non-donor parent or a healthy, unrelated control, their immune cells reacted normally and flourished. They further stressed the need for more studies to be conducted to evaluate if comparable results can be reached in allograft recipients who had a healthy pre-transplantation T-cell immunity and hematopoiesis. (MedPage Today June 15, 2022)