CAD is a condition that makes your body’s immune system attack your red blood cells and destroy them. It’s triggered by cold temperatures, and it can cause problems that range from dizziness to heart failure. How It Happens antibodies help you fight off infections. Some types of antibodies are called cold agglutinins, because they’re triggered when you’re in temperatures between freezing and 50 degrees F. With CAD, those antibodies MISTAKENLY attach themselves to red blood cells instead of to bacteria or viruses and eventually kill the red blood cells and this will lead to anemia.