A few antiviral cells might prevent Bone Marrow Transplant infections

Bone marrow transplantation is a life-saving therapy for patients with blood cancers like leukemia or lymphoma. However, the depletion of the patient’s immune system prior to transplantation can put patients at risk of an infection by a virus called cytomegalovirus (CMV) that can be life-threatening in these immune-compromised individuals.
Now, researchers have found that a very small subset of antiviral immune cells transplanted along with a donor’s blood stem cells could be enough to fight and even prevent the disease caused by CMV.
Between 50% and 80% of adults in the United States are infected with CMV, although the virus is kept under control by a healthy immune system. In patients with weakened immune systems, however, CMV can become reactivated and cause life-threatening pneumonia, among other symptoms. Current treatment includes antiviral medications, but these are not always well tolerated by patients and they also harm the very cells that bone marrow transplantation aims to replenish.
“We know that re-establishment of antiviral immunity in these patients is critical to fully control cytomegalovirus in bone marrow transplant recipients,” said the study’s senior author, Christopher Snyder, Ph.D., an assistant professor of microbiology and immunology at Thomas Jefferson University. “Our study suggests that, in addition to infusing stem cells that restore the bone marrow, lifelong anti-CMV immunity may be rapidly restored by also infusing a subset of antiviral immune cells that have stem cell-like properties.”
Currently, investigators around the world are experimenting with restoring the immune cells responsible for keeping CMV in check by transplanting those specific antiviral cells from healthy donors, a type of immunotherapy. “The problem,” said Dr. Snyder, “is that current methods for selecting antiviral immune cells may inadvertently limit the ability of those cells to restore lifelong immunity.”
Researchers have focused on developing anti-CMV immunotherapy around the “fighter” cells, called CD8 T effector cells, that attack and kill virally infected host cells. These cells are selected and expanded in the lab to increase their numbers, but this process may limit their lifespan and ability to divide.
The infused memory cells became major contributors to the recipient antiviral immune response, persisting for at least 3 months of time and producing the “fighter” cells at a steady stream.
“This may be a valuable approach to keep the disease from emerging in people.”
“Our data argue for developing new clinical trials focused specifically on using these T memory cells, in order to determine if it would indeed be better than current therapeutic options,” said Dr. Snyder.