If you are found to be eligible to take part in this study, you will receive GM-CSF as an injection under the skin, three times a week for eight weeks. You will receive rituximab by vein, once a week for four weeks. Usually, the first dose of rituximab requires several hours to complete. Later doses should usually be shorter, but may vary according to individual tolerance. Acetaminophen (Tylenol), diphenhydramine hydrochloride (Benadryl), and steroids (hydrocortisone or similar) will be given before rituximab to decrease the risk of side effects. If side effects do occur during the infusion, you will need to stay at the hospital and be observed until the side effects have gone away. Other than that, treatment will be given on an outpatient basis.