New method changes leukemia cells into immune cells

Researchers, including one of Indian-origin, have found a new method that can force dangerous leukemia cells in the lab to mature into immune cells that may help fight cancer.

B-cell acute lymphoblastic leukemia with a mutation called the Philadelphia chromosome is a particularly aggressive  cancer with poor outcomes, said Ravi Majeti, an assistant professor at the  Stanford University  School of Medicine and senior author of the study.

Majeti and his colleagues collected leukemia cells from a patient and were trying to keep the cells alive in a culture plate. Postdoctoral scholar Scott McClellan mentioned that some of the cancer cells in culture were changing shape and size into what looked like harmless immune cells known as macrophages.

Majeti agreed with that observation, but the reasons for the changed cells were a mystery until he remembered an old research paper, which showed that early B-cell mouse progenitor cells could be forced to become macrophages when exposed to certain transcription factors - proteins that bind to certain DNA sequences.

"B-cell leukemia cells are in many ways progenitor cells that are forced to stay in an immature state," Majeti said.

Majeti, McClellan and Christopher Dove, an MD/PhD student, did more experiments and confirmed that methods shown to have altered the fate of the mouse progenitor cells years ago could be used to transform these human cancer cells into macrophages, which can engulf and digest cancer cells and pathogens.

Majeti and his colleagues hope that when the cancer cells become macrophages they will not only be neutralised but may actually assist in fighting the cancer.

"Because the macrophage cells came from the cancer cells, they will already carry with them the chemical signals that will identify the cancer cells, making an immune attack against the cancer more likely," Majeti said.

The researchers' next steps would be to see if they can find a drug that will prompt the same reaction and that could serve as the basis for a therapy for the leukemia.

The study is published in the journal Proceedings of the National Academy of Sciences.