In vivo immunoadsorption of antipig antibodies in baboons using a specific Gal alpha 1-3Gal column

The major role of anti-alpha Gal antibodies in the hyperacute rejection of pig organs by humans and baboons has been clearly demonstrated, Spacered alpha-galactose disaccharide (Gal alpha 1-3Gal) hapten was produced by chemical synthesis and covalently attached to a flexible, hydrophilic polymer (PAA), which in turn was covalently coupled to macroporous glass beads, forming an immunoadsorbent that is mechanically and chemically stable and can be sterilized, The extracorporeal immunoadsorption (EIA) of anti-alpha Gal antibodies using this column has been investigated in vivo in 3 baboons, In Baboon 1 (which had hyperacutely rejected a pig heart transplant 4 months previously, was not splenectomized, and did not receive any pharmacologic immunosuppression) the levels of anti-alpha Gal antibody and antipig IgM and IgG, as well as serum cytotoxicity, fell significantly after each of 3 EIAs but were not eliminated, Serum cytotoxicity, antipig immunoglobulin and anti-alpha Gal antibody rose steeply within 24 hr of the final EIA, suggesting that the return of cytotoxicity was associated with anti-alpha Gal antibody, In Baboons 2 and 3 (which were immunologically naive and splenectomized, and received triple drug immunosuppressive therapy) serum cytotoxicity was totally eliminated and anti-alpha Gal antibody and antipig IgM and IgG levels were greatly reduced by courses of EIA. In Baboon 2, cytotoxicity and all antibody levels remained negligible for approximately one week after the final (fourth) daily EIA, In Baboon 3, cytotoxicity and antibody levels were maintained low by intermittent EIA (over a period of 13 days) for almost 3 weeks, although antipig IgM began to rebound 4 days after the final EIA, We conclude that, in an immunosuppressed, splenectomized baboon, repeated EIA using a specific alpha Gal disaccharide column will reduce antipig and anti-alpha Gal antibody levels and serum cytotoxicity significantly for several days, This reduction in cytotoxicity will almost certainly be sufficient to delay the hyperacute rejection of a transplanted pig organ, but further studies are required to investigate whether it will be sufficient to allow accommodation to develop.