Removal of xenoreactive antibodies by protein-A immunoadsorption: experience in 22 patients

Characteristics of protein-carbohydrate interactions as a basis for developing novel carbohydrate-based antirejection therapies

The relative shortage of human organs for transplantation is today the major barrier to a broader use of transplantation as a means of treating patients with end-stage organ failure. This barrier could be partly overcome by an increased use of blood group ABO-incompatible live donors, and such trials are currently underway at several transplant centres. If xenotransplantation can be used clinically in the future, the human organ shortage will, in principle, be eradicated. In both these cases, carbohydrate antigens and the corresponding anti-carbohydrate antibodies are the major primary immunological barriers to overcome. Refined carbohydrate-based therapeutics may permit an increased number of ABO-incompatible transplantations to be carried out, and may remove the initial barriers to clinical xenotransplantation. Here, we will discuss the chemical characteristics of protein-carbohydrate interactions and outline carbohydrate-based antirejection therapies as used today in experimental as well as in clinical settings. Novel mucin-based adsorbers of natural anti-carbohydrate antibodies will also be described.

Non-specific removal of antibodies in patients with idiopathic dilated cardiomyopathy: implications for xenotransplantation

We assessed the efficiency of non-specific extracorporeal immunoadsorption (EIA), using polyclonal anti-human immunoglobulin antibodies, in depleting the serum of anti-galactosealpha1,3galactose (Gal) antibody and in decreasing serum cytotoxicity in 5 patients with idiopathic dilated cardiomyopathy. The mean concentrations of anti-Gal immunoglobulin (Ig)M and IgG before EIA were 74 microg/ml and 159 microg/ml, respectively. After EIA, these concentrations decreased by 86% and 88%, respectively. Both anti-Gal IgM and IgG returned to pre-EIA concentrations within 1 month, without rebound to greater than baseline concentrations. After EIA, mean serum cytotoxicity also decreased from 90% to 17%, with recovery by 1 month. Extracorporeal immunoadsorption proved safe in patients with heart failure and was effective in depleting anti-Gal antibody and in decreasing serum cytotoxicity to pig cells.