Refinements to life-saving T-cell therapy that protects bone-marrow transplant patients from severe infections now allow for the treatment of more and more patients, and many of these are children.

T-cells are a type of specialized white blood cell of critical importance to our immune system. It's central to adaptive immunity, or the system that tailors our body's immune response to specific pathogens. T-cells are akin to soldiers that hunt down and destroy invading pathogens.

Experimental T-cell therapy aims to assist bone-marrow transplant patients during a vulnerable period after the procedure, which is the first few months where the recipient's defenses against viruses are severely weakened. It's during this time period where the body is rebuilding its natural defenses.

After two decades of clinical trials, T-cell therapy technology has substantially improved to the point where its use is becoming more widespread. A well-documented case saw this experimental T-cell therapy save the life of a boy born with a very rare hereditary disease called chronic granulomatous disease (CGD). Only about 20 cases of CGD are recorded in the United States every year.

CGD is a diverse group of hereditary diseases where certain immune system cells have difficulty forming the reactive oxygen compounds used to kill certain ingested pathogens. This inability leads to the formation of granulomata in many organs. A granuloma is an organized collection of macrophages, which are a type of white blood cell that engulfs and digests cellular debris, foreign substances, microbes and cancer cells among others.

In one such successful case using T-cell therapy, the elder brother of a young boy with CGD donated his "supercells"or T-cells to his little brother. Doctors said the younger brother's white blood cells were incapable of fighting off bacterial and fungal infections. They feared a simple bacterial infection, of almost no concern in a healthy child, might spread out of control in his young body.

In April 2018, doctors "cleansed" the younger brother's marrow using chemotherapy. They took a small amount of marrow from Thomas's hip bones. They extracted supercells (or stem cells) from this sample, which they re-injected into Johan's veins. Those cells eventually settled in the younger brother's bone marrow and began producing normal white blood cells.

The next vital step was preventive cell therapy under an experimental program led by immunologist Michael Keller at Children's National Hospital (CNH) in Washington D.C., which is among the top six children’s hospitals in the U.S.

Keller used an incubator to grow white blood cells to be implanted into the younger brother, thereby quickly boosting his immune system. Doctors at CNH extracted the T-cells that had already encountered six viruses. Keller grew these T-cells for 10 days in an incubator. The process saw the creation of an army of hundreds of millions of specialized T-cells.

These T-cells were then injected into the younger brother's veins, immediately conferring protection against the six viruses.

"He has his brother's immune system," said Keller.

blood cells
Multiple myeloma is a blood cancer formed by malignant plasma cells. Photo courtesy of Pixabay