Scientists have improved a method for bone marrow transplantation from mismatched donors that would help restore the immune system quicker, according to findings presented at the American Society of Hematology Annual Meeting and Exposition in New Orleans in December.

In a collaborative study, Prof. Yair Reisner of the Weizmann Institute’s immunology department and Prof. Massimo Martelli, head of the hematology and clinical immunology section at the University of Perugia, teamed up to find a way to facilitate immune response recovery in T-cell–depleted bone marrow transplant recipients.

According to background information provided by the authors, although removing donor T cells from the bone marrow reduces the risk of graft-versus-host disease, the immune system is slow to recover after the transplant, which leaves the patient at risk of serious infection.

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For the study, scientists purified regulatory T cells (T regs) from donor’s blood and infused this intravenously into 300 leukemia and lymphoma patients who received mismatched “mega dose” T-cell–depleted stem cell transplants. The cancer patients had previously undergone standard radiation and chemotherapy treatment.

The results revealed that 25 of 26 patients experienced prompt immune recovery and their immune systems were functioning well several months later. The patients who underwent the new procedure showed quick, lasting improvements in immune activity. Most patients experienced no symptoms even though they received large doses of T cells that are generally associated with lethal graft-versus-host disease.

“Further follow up on these patients and additional clinical trails will be need before the procedure can be widely adopted,” the authors explained. “But these results strongly suggest that T regs used in mega-dose stem cells will further enhance the cure rate for bone marrow transplant patients without a matched donor in the family.”