ANTICARBOHYDRATE ANTIBODIES ASSOCIATED WITH HYPERACUTE REJECTION IN AVASCULARIZED MOUSE HEART-TO-RAT XENOTRANSPLANTATION MODEL - CHARACTERIZATION OF ANTI-FORSSMAN ANTIBODIES

work was undertaken to determine carbohydrate structure for antibody r esponse in the experimental xenograft model mouse-to-rat. Glycolipids were prepared from nine different mouse organs and separated for carbo hydrate size on thin layer plates, Sera taken from normal untreated ra ts showed only weak or absent IgM antibody-binding to the separated mo use glycolipids, This is in accordance with the observation that mouse heart grafts are not hyperacutely rejected by the rat, However, sera taken from mouse heart xenografted rats show clear IgG and IgM antibod y binding to neutral glycolipids migrating in the five-sugar region of the thin-layer plate. These rats have previously been reported to hyp eracutely reject a second xenograft, Glycolipids with this particular mobility and immunostaining properties are the dominant ones in the mo use caval vein preparation, which probably represents a rather pure va scular structure. The target antigen structure was identified, by mass spectrometry and proton nuclear magnetic resonance spectroscopy, to b e the Forssman pentaglycosylceramide. A commercial monoclonal antibody directed toward the Forssman antigen bound the same biochemical struc ture as the antibodies derived from the mouse heart-xenografted rats, Most of the IgM activity, but very little of the IgG activity was adso rbed using the Forssman terminal disaccharide solid phase adsorbent. T his definition of a carbohydrate target structure may facilitate exper imental xenograft studies.