Lower Titers of IgA Antibodies to Pneumococcal Polysaccharide Antigens after Vaccination are a Risk Factor for Development of Bacterial Infection after Heart Transplantation

Purpose Bacterial infections are the most frequent infectious complications after heart transplantation. IgA and IgM serological response to the 23-valent pneumococcal polysaccharide vaccine (PPSV23) can be used to assess antibody function against T-cell independent type-2 antigens (anti-PPS). We evaluated if IgA and IgM anti-PPS titers after vaccination in a cohort of heart recipients were associated with the risk for development of bacterial infections. Methods A prospective follow-up study of 151 adult heart recipients (124 male, 27 female, mean age: 58 years) at a single center. The study population received one injection of PPSV23 before transplantation. Specific IgA and IgM anti-PPS were measured in pre and post vaccination sera before transplantation by ELISA (2-3 weeks interval between pre and post vaccination samples) and at distinct times after transplantation (day 7, 30, 90, 180). ELISA plate contained the 23 antigens of the pneumococcal vaccine. The prevalence of bacterial infections was registered during the first 6 months after transplantation. Results During follow-up 32 patients (21%) developed bacterial infectious complications that required IV drug therapy in hospital. Mean anti-PPS titers were significantly lower in transplanted patients who developed bacterial infections as compared with heart recipients who remained free of bacterial infections: after vaccination before transplantation (IgA anti-PPS, 12±10 vs 27±51 mg/dL, p=0.031), at day 7 after transplantation (IgA anti-PPS, 6±5 vs 13±12 mg/dL, p=0.01), at day 30 after transplantation (IgA anti-PPS, 6±5 vs 19±34 mg/dL, p=0.003 and IgM anti-PPS, 6±4 vs 14±19 mg/dL, p=0.002), at day 90 (IgA anti-PPS, 4±2 vs 17±10 mg/dL, p=0.003 and IgM anti-PPS, 7±4 vs 13±8 mg/dL, p=0.04) and at day 180 (IgA anti-PPS, 3±1 vs 15±9 mg/dL, p=0.003). Conclusion Low IgA and IgM anti-polysaccharide responses may predispose heart recipients to develop bacterial infections. IgA anti-PPS as a biomarker warrants validation in a multicenter study.