Elucidation of the Mechanism of IVIG-Associated Hemolysis

All IVIG orders received by the blood transfusion service at participating sites will be screened for patient eligibility. All non-O blood group patients receiving a cumulative 28-day dose of IVIG ≥ 2 g/kg will be approached for enrolment. Exclusion criteria include the presence of an alternate cause of anemia, including blood loss, other drug-induced hemolysis, anemia associated with chemotherapy for cancer, or hemolysis associated with an underlying disease or participation in another ongoing study. Patients receiving repeated courses of therapy will be eligible for re-enrollment a maximum of 6 times. There are otherwise no exclusions on the basis of age, diagnosis, concurrent treatment, or specific brand of product received. Enrolment will occur at multiple Canadian health care facilities.

Upon enrolment,case report forms documenting the participant's previous medical history, IVIG treatments and adverse reactions, and concurrent medication use will be collected. Laboratory testing for hemolysis will be performed at baseline, immediately following the completed high-dose cycle (usually administered over 1-2 days), and then again at 5-10 days post-infusion. IVIG associated. Hemolysis will be defined and graded as per the criteria of the Canadian IVIG Pharmacovigilance Group. The pathophysiology of IVIG-associated hemolysis will be characterized by tracking changes in serum complement levels, performing extended cytokine profiling, and conducting mononuclear phagocyte activity assays using patient monocytes. Secretor gene status, ABO zygosity and FcR polymorphisms will also be determined. A predictive model incorporating both patient factors (eg., blood group, total dose prescribed, presence of pre-infusion inflammation) and product factors (eg., specific lot number) will then be developed.