Participants take rituximab for 12 weeks. One dose of the drug is infused through an arm vein over about 30 minutes on either day 1 (the first dose) or day 3 (the second dose). All other doses are given as an injection under the skin. After the first week, patients can choose to do these injections at home. Rituximab will be given 3 times a week for a total of 12 weeks. Other medications are given to reduce the side effects and allergic reactions to the drug. In addition to treatment, patients undergo the following tests and procedures: