Neutrophil

One litre of human blood contains about five billion neutrophils (around half of all white blood cells).

Chris learned that his level of infection-fighting neutrophil cells, normally churned out by the bone marrow, had fallen so low that his defenses were in tatters.

All mammals naturally make hypochlorous acid to fight infection. When you cut yourself, for instance, white blood cells known as neutrophils go to the site of injury, capturing any invading pathogens.