By Dr. Nitin Thyagaraja What Is Lupus? Lupus (Systemic Lupus Erythematosus, or SLE) is a long-term autoimmune illness. The immune system  protects the body by recognizing and destroying harmful germs like bacteria and viruses, while usually leaving the body’s own healthy cells unharmed. As the word states, "auto-immunity" is a condition where your immune system becomes overactive and starts attacking healthy parts of your own body. It can affect your skin, joints, kidneys, bl