Immune response in patients receiving a bioprosthetic heart valve: lack of response with decellularized valves

Conventional biological heart valves treated with glutaraldehyde (GA) reveal a limited lifespan due to calcification. This is assumed to be an immune response initiated process, which is not seen with decellularized valves. However, their immunological potential is still a matter of debate. Therefore, serum samples from patients undergoing heart valve surgery were obtained before (Pre), after (Post), and 9-12 months after operation (Follow Up). Immunoglobulin G (IgG) and M (IgM) antibodies against porcine collagen I and α-Gal (Gal-alpha1,3-Gal-beta1,4-GlcNac-R) were determined for decellularized and GA treated valves. Antibody titers for collagen type I revealed no significant alteration for both types of valves. However, a considerable anti-α-Gal antibody response was observed in patients with GA-treated porcine valves. In detail, IgM antibodies were increased during follow up (p<0.05), whereas decellularized valves revealed a minor decrease in the IgM response (p<0.001). IgG antibodies were considerably increased with GA-treated porcine (p<0.05) and bovine (p<0.01) xenografts, whereas there was lack of response with decellularized valves. This indicates that GA treatment is not sufficient to eliminate immune response to the α-Gal epitope completely. Future investigations will have to verify whether immune response to α-Gal can be linked to the limited durability of conventional valves.