Patients with Leukemia have cancerous white blood cells and people with Autoimmune Disorders like Rheumatoid Arthritis have white blood cells that are hypersensitive and attack healthy cells. Since they both have white blood cells in common, we can cure many diseases with the same treatment.

The solution is to replace the faulty white blood cells with healthy ones. This involves killing off the bad cells first with medicine that is specifically targeted to kill white blood cells and does not cause significant damage to other cells in the body.

However, without an immune system our bodies would rapidly become hosts to a variety of harmful organisms. So we need to provide the patient with a sterile / germ free environment and possibly antibiotics during the treatment, because they would be temporary without a fully functioning immune system.

After the faulty white blood cells are either dead or considerably fewer in number. The next step is to inject the bone marrow with stem cells that were made from the patient. This is accomplished by taking healthy adult cells from another part of the patient's body and then turning a tissue sample into stem cells using the latest breakthrough in stem cell research. The stem cells then differentiate into healthy bone marrow, which produces healthy white blood cells. Stem cells could also be differentiated directly into white blood cells with chemicals to trigger the differentiation process. However, the patient would be dependent on periodic injections of healthy white blood cells grown in the lab.

So there it is, a potential cure for Leukemia, Rheumatoid Arthritis, and a host of other nasty autoimmune diseases.