Removing one blood stem cell type rejuvenated old mice's immunity

Researchers at Stanford University and the National Institutes of Health targeted those biased stem cells directly in old mice, using an antibody designed to clear out only the stem cells skewed toward producing inflammation-related blood cells.

After depleting those myeloid-biased stem cells, old mice regained several hallmarks of a younger immune system, including more of the progenitor cells that give rise to infection-fighting lymphocytes, more naive T cells, and more naive B cells. The treated old mice also mounted stronger primary and secondary immune responses to a viral infection than untreated old mice.

The experiment pointed to two separate populations of blood stem cells, one myeloid-biased and one balanced, rather than a single population that gradually drifts with age, and removing just the biased population shifted the whole system back toward a younger balance. The work was done entirely in mice, and whether a similar antibody could safely clear the same cells in aging humans has not been tested.

One cell type gone, immunity renewed.