IgG2 Insufficiency before Heart Transplantation as a Risk Factor of Early Deadly Infections

Abstract

Purpose The IgG antibody response against polysaccharide microbial antigens is enriched for IgG2 antibodies, which possess characteristics that are likely to enhance opsonisation of these antigens. IgG2 molecules are more effective than other IgG subclasses in opsonising antigens with a high epitope density. Lower IgG2 concentration has been found to be a risk factor of death after community acquired pneumonia. Infection is still a major cause of death during the first year after heart transplantation. In this study we evaluated the prevalence of IgG2 insufficiency in heart recipients before transplantation and its relationship with the risk for development of severe deadly infections. Methods 119 patients evaluated in a single center were included. Prospective follow-up was performed to identify the clinical outcomes: early deadly infections during the first month and deadly infections during the follow-up after transplantation. In this study using the Binding Site nephelometry test, IgG2 insufficiency was defined as IgG2 levels below 2.72 mg/dL. Results In the pre-transplant evaluation 46 (38.7%) patients were found to have IgG2 insufficiency. Early deadly infections were more prevalent among patients with IgG2 insufficiency (RH 2.68, 95% CI 1.10-6.53, p=0.029). Use of mechanical ventilation, pre-transplant infections and pre transplant use of ventricular assist devices were risk factors of early deadly infections. In multivariate regression analysis IgG2 insufficiency remained in the model (RH 4.18, 95% CI 1.20-14.47, p=0.024). IgG2 insuficiency was also a risk factor of deadly infections (RH 4.27, 95% CI 1.37-13.26, p=0.012) and a risk factor of 1-year all-cause mortality (RH 2.68, 95% CI 1.10-6.53, p=0.029). Conclusion Pre-transplant IgG2 insufficiency is a risk factor of bad outcome after transplantation. This immunological biomarker warrants evaluation in a multicenter study.