Pullulan and restpullulan preparations were found to be antigenic in man.
Pullulan and restpullulan cross-reacted strongly with types II and IX anti-pneumococcal sera. In the type II cross-reaction pullulan was more efficient than restpullulan per unit weight while in the type IX cross-reactions restpullulan, water-restpullulan and partially hydrolyzed fractions of restpullulan all reacted better than did pullulan.
Pullulan precipitated all of the antibody in type II antiserum cross-reacting with Friedländer B polysaccharide and most of the antibody crossreacting with dextran. The pullulan anti-type II cross-reaction was inhibited strongly by glucuronic acid and not at all or but very slightly by various glucose oligosaccharides. The immunochemical findings are of interest in relation to the demonstration by Wallenfels of a uronic acid in pullulan.
The cross-reaction of restpullulan with type IX antiserum is inhibited best by nigerose and maltotriose which are considerably better than maltose. Kojibiose, isomaltotriose and isomaltose were much less effective. The findings are consistent with the specificity of antibody in type IX antiserum cross-reacting with restpullulan being related to α 1,4 and α 1,3 linked glucoses.