Rituximab and/or Lenalidomide in Treating Patients With Follicular Non-Hodgkin's Lymphoma That is Not Refractory to Rituximab

Outline: This is a randomized, multicenter study. Patients are randomized to 1 of 3 treatment arms. Please see the "Arms" section for a description of each treatment arm. The primary and secondary objectives of the study are provided below. Primary Objectives: * To determine the response rate (overall and complete) after lenalidomide therapy and rituximab + lenalidomide in follicular NHL patients who have relapsed. * To determine time to progression after lenalidomide therapy and rituximab and lenalidomide in follicular NHL patients who have relapsed. Secondary Objectives: * To compare the time to progression of the previous rituximab regimen to that obtained subsequently to lenalidomide therapy and rituximab + lenalidomide. * To determine the toxicity profile of lenalidomide therapy and of rituximab and lenalidomide in follicular NHL patients who have received a previous rituximab regimen. * To correlate Fc receptor polymorphism profiling with response to lenalidomide or rituximab + lenalidomide in previously treated patients with follicular NHL who have relapsed. * To evaluate changes in Natural Killer (NK) cells, activated NK cells, activated T-cells and several plasma cytokines followed by rituximab therapy and correlation of observed changes to objective response rates. After completion of study treatment, patients are followed for up to 10 years from study entry.