A red and a white blood cell. (Steve Gschmeissner/Sciece Photo Library/Getty Images) PETER COCKERILL & DAVID C. WRAITH, THE CONVERSATION 22 JUNE 2020 For most of us, the immune system works to protect us from bacteria, viruses, and other harmful pathogens. But for people with autoimmune conditions, the body's white blood cells instead perceive other cells and tissues in the body to be a threat and attacks them.