Anti alpha-Gal Immune Response Following Porcine Bioprosthesis Implantation in Children

Background and aim of the study: Porcine bioprostheses have been widely used in cardiac surgery in the treatment of valvular heart disease. However, in younger patients, their use has been limited by early failures known to be associated with an immune response and subsequent degeneration. The natural antibodies directed at Galα1, 3-Galβ1-4GlcNAc-R(αGal), have been thought to initiate an immune response in humans transplanted with porcine organ xenografts. The study aim was to determine the anti α-Gal immune response following commercial porcine bioprosthesis implantation in children. Methods: Between January 2008 and April 2008, 19 consecutive patients underwent pulmonary valve replacement (PVR) with a commercially available porcine bioprosthesis for an incompetent pulmonary valve with congenital heart diseases. The median age at surgery was 132 months (range: 14-330 months). Previous PVR with a porcine bioprosthesis had been performed in seven patients at a median of 44 months (range: 26-117 months) before surgery (rePVR group). Sera were obtained sequentially five times: immediately before surgery, and at one day, one week, three weeks, and two months postoperatively. All serum samples were analyzed using an enzyme-linked immunosorbent assay to investigate the α-Gal immune response. Results: There were no operative deaths or complications. There was no statistically significant difference between the titers of anti α-Gal antibodies of the PVR and re-PVR groups. The titer of anti α-Gal antibodies (IgM and IgG) was decreased on the first postoperative day, but increased in the first postoperative week, regardless of the isotype. Whilst the titer of the anti α-Gal IgM antibody began to decrease after three weeks postoperatively, the titer of anti α-Gal IgG antibody remained increased after two months. Conclusion: The implantation of a porcine bioprosthesis elicits the increased formation of anti α-Gal antibodies during the early postoperative period in children, with different patterns between the two isotypes. The IgM antibody response was rapid and transient, while the IgG antibody response was longer and more delayed.