Immune cells long considered lowly foot soldiers on the front line against bacteria and fungi turn out to have a commanding role. Researchers report that neutrophils, the most common white blood cells in humans, control the activity of another antimicrobial white blood cell — the natural killer cell.

Sophie Ugolini and Eric Vivier of Aix-Marseilles University in France and their colleagues isolated a mutant mouse whose natural killer cells responded poorly to stimulation. The mutant, they found, lacked mature neutrophils. Without neutrophils to guide them, mouse natural killer cells failed to mature or function properly. The same was true of natural killer cells in human patients with low neutrophil counts, a condition known as neutropenia.

J. Exp. Med. http://dx.doi.org/10.1084/jem.20111908 (2012)