Brief Summary: Biological therapies, such as MDX-010, work in different ways to stimulate the immune system and stop cancer cells from growing. This phase I/II trial is studying the side effects and best dose of MDX-010 and to see how well it works in treating patients with recurrent or refractory B-cell non-Hodgkin's lymphoma.

Detailed Description: PRIMARY OBJECTIVES: I. To characterize the safety profile of MDX-010 (ipilimumab) monoclonal antibody and identify a tolerable immunologically active dose level in B cell lymphoma patients. II. To evaluate the clinical response rate in B cell lymphoma patients treated with MDX-010. SECONDARY OBJECTIVES: I. To evaluate the phenotype and function of memory T cells before and after treatment with MDX-010 by: * Quantitation and phenotypic characterization of peripheral blood and tumor infiltrating T-cells, including cluster of differentiation (CD)4+CD25+ regulatory T cells. * Measurement of tumor-specific T cells in peripheral blood lymphocytes. * Measuring proliferation of memory T cells in response to recall antigens (tetanus toxoid and keyhole limpet hemocyanin \[KLH\]). II. Measurement of anti-tumor antibodies in serum pre- and post-therapy. III. To evaluate the time to progression. IV. To evaluate the duration of response to treatment with MDX-010. OUTLINE: This is a multicenter, open-label, phase I, dose-escalation study followed by a phase II study. Patients are grouped according to prior treatment with a vaccine therapy for lymphoma (yes vs no). PHASE I: Patients receive anti-cytotoxic T-lymphocyte-associated antigen-4 monoclonal antibody (MDX-010) IV over 90 minutes on day 1. Treatment repeats every 28 days for a total of 4 courses in the absence of disease progression or unacceptable toxicity. Cohorts of 6 patients from each group receive escalating doses of MDX-010 until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose-limiting toxicity. PHASE II: Patients receive MDX-010 as in phase I at the MTD. Patients are followed at 1 and 4 months and then every 6 months for up to 2 years.