RecruitingPhase 3Drug trialA Clinical Trial to Evaluate Efficacy, Safety, and Pharmacokinetics of Gamunex in Participants With Chronic Lymphocytic Leukemia, Multiple Myeloma, or Non-Hodgkin LymphomaThe main goal of this study is to show that people with certain immune problems (from Chronic Lymphocytic Leukemia, Multiple Myeloma, or Non-Hodgkin Lymphoma) get fewer serious infections when they receive Gamunex C through an IV once every 4 weeks, along with their usual medical care, for one year. All participants will receive Gamunex-C 500 mg/kg once every 4 weeks (total 13 doses) starting Day 1 (Week 1) through Week 48 (end of Treatment Phase).