Immunoglobulin G levels before and after lung transplantation

Rationale: The determinants of immunoglobulin G (IgG) level and the risk of hypogammaglobulinemia (HGG) in patients with severe lung disease before and after lung transplantation are unknown. Objectives: We aimed to identify predictors of low IgG levels before and after lung transplantation. Methods: We performed a retrospective cohort study of 40 consecutive lung transplant recipients at our center. Total IgG levels were measured before and serially after transplantation. Mild HGG was defined as IgG levels from 400-699 mg/dl; severe HGG was defined as IgG levels < 400 mg/dl. Measurements and Main Results: Before transplantation, six (15%) patients had mild HGG, and none had severe HGG. Patients with chronic obstructive pulmonary disease had lower IgG levels compared with patients with other diseases (independent of corticosteroid use and age; p = 0.001) and an increased risk of mild HGG (p = 0.005). The cumulative incidences of mild and severe HGG significantly increased after transplantation (58 and 15%, respectively, both p < 0.04 compared with pretransplant prevalences). Lower pretransplant IgG level and treatment with mycophenolate mofetil were associated with lower IgG levels after transplantation (both p < 0.05). Only lower pretransplant IgG levels were significantly associated with an increased risk of severe HGG after transplantation (p = 0.02). Conclusions: Mild HGG is common in patients with severe chronic obstructive pulmonary disease, and the incidences of mild and severe HGG increase significantly early after lung transplantation. Baseline IgG levels and treatment with mycophenolate mofetil affect post-transplant IgG levels.