Immunological studies of phytohaemagglutinin. I. Reaction between phytohaemagglutinin and normal sera

Abstract

Studies of the precipitation of normal human serum by the kidney bean phytohaemagglutinin, Phaseolus vulgaris (PHA), showed that the main serum components involved were α₂-macroglobulin, β-lipoproteins and γM immunoglobulins. Preparations of α₁-glycoprotein, orosomucoid and some γA immunoglobulins were also precipitated by PHA. Antisera prepared against the PHA—NHS precipitate recognized α₂-macroglobulin, β-lipoproteins and γM immunoglobulins, γG immunoglobulins and at least four other unidentified antigens in the β and α regions. PHA did not react with B or A, O blood group substances.

Concanavalin A, a jack bean agglutinin, precipitated the same proteins which were precipitated by Phaseolus vulgaris PHA but a Dolichos biflorus extract did not react with human serum. Incomplete chemical studies of this interaction suggested that even though the same serum proteins were precipitated by Concanavalin A and PHA, the sugar specificity, if involved, is different for both lectins.

Incomplete studies of the component or components of PHA involved in the PHA—NHS interaction suggested that three cathodally migrating proteins were recognized by both the antisera to PHA and to the precipitate formed by PHA and normal human serum.