What Exactly Is Lupus?

Our immune system is an incredible thing. It’s a complex, disease-fighting machine, capable of fending off attacks from bacteria and viruses. But what happens when that same incredible system stops fighting diseases, and starts attacking you?

SICK is a new series that looks at how diseases actually work inside our body. We'll be visiting medical centers and talking to top researchers and doctors to uncover the mysteries of viruses, bacteria, fungi and our own immune system. Come back every Tuesday for a new episode and let us know in the comments which diseases you think we should cover next.