What colored blood cells fight off infection?

White blood cells protect your body against infection. As your white blood cells travel through your bloodstream and tissues, they locate the site of an infection and act as an army general to notify other white blood cells of their location to help defend your body from an attack of an unknown organism. Once your white blood cell army arrives, they fight the invader by producing antibody proteins to attach to the organism and destroy it.

Source: Cleveland Clinic