 ARM B: Patients receive rituximab IV over 2-6 hours once weekly in weeks 1-4 and ipilimumab IV over 90 minutes once weekly in weeks 3, 6, 9, and 12. Patients then receive ipilimumab IV over 90 minutes and rituximab IV over 2-6 hours once every 12 weeks for up to 1 year in the absence of disease progression or unacceptable toxicity. 