Evaluation of humoral immunity profiles to identify heart recipients at risk for development of severe infections: A multicenter prospective study.

Background: New biomarkers are necessary to improve detection of the risk of infection in heart transplantation. We performed a multicenter study to evaluate humoral immunity profiles that could better enable us to identify heart recipients at risk of severe infections.

Methods: We prospectively analyzed 170 adult heart recipients at 8 centers in Spain. Study points were before transplantation and 7 and 30 days after transplantation. Immune parameters included IgG, IgM, IgA and complement factors C3 and C4, and titers of specific antibody to pneumococcal polysaccharide antigens (anti-PPS) and to cytomegalovirus (CMV). To evaluate potential immunologic mechanisms leading to IgG hypogammaglobulinemia, before heart transplantation we assessed serum B-cell activating factor (BAFF) levels using enzyme-linked immunoassay. The clinical follow-up period lasted 6 months. Clinical outcome was need for intravenous anti-microbials for therapy of infection.

Results: During follow-up, 53 patients (31.2%) developed at least 1 severe infection. We confirmed that IgG hypogammaglobulinemia at Day 7 (defined as IgG <600 mg/dl) is a risk factor for infection in general, bacterial infections in particular, and CMV disease. At Day 7 after transplantation, the combination of IgG <600 mg/dl + C3 <80 mg/dl was more strongly associated with the outcome (adjusted odds ratio 7.40; 95% confidence interval 1.48 to 37.03; p = 0.014). We found that quantification of anti-CMV antibody titers and lower anti-PPS antibody concentrations were independent predictors of CMV disease and bacterial infections, respectively. Higher pre-transplant BAFF levels were a risk factor of acute cellular rejection.

Conclusion: Early immunologic monitoring of humoral immunity profiles proved useful for the identification of heart recipients who are at risk of severe infection.