Patients who have immune mediated diseases commonly undergo plasma exchange (PLEX) procedures to remove pathological substances, typically believed to be antibodies. At our facility about 400 of these procedures are performed annually on 40-60 different patients. These procedures are considered within the standard of care for these patients and are covered by insurance. This study will not influence the treatment plan for subjects who participate in this study. The goal of the study is to collect and cryopreserve blood biospecimens (plasma, serum, PBMCs) for current and future studies. Any patient undergoing plasma exchange procedures will be eligible for the study. Patients or the legally authorized representative (LAR) will be consented for the study as soon as feasible after the are referred to DeGowin for plasma exchange. The immediate objective of the study is to examine antibody levels (IgG/IgM) and BAFF levels in the blood of these patients over the course of the plasma exchange treatments. Specimens and clinical data will be collected such that other immune factors that may regulate B cell survival, proliferation and antibody secretion can be studied. Another goal of the study is to isolate and cryopreserve PBMCs at different points during the patient's treatment. This would allow the study of immune cells that may mediate these diseases. The study will also follow pathological antibodies over time in these patients so biospecimens can be obtained even after the completion of their course of plasma exchange treatments. The collection of biospecimens and clinical information from these subjects will help us understand the impact of plasma exchange on both normal and pathological immune factors in a variety of patients undergoing these procedures.