Tolerance in Adult Rats to a Purified Protein, Flagellin, from Salmonella adelaide

Abstract

THE capacity of flagellar antigens from Salmonella adelaide to induce immunity and tolerance in rats has been described in detail before¹. The monomeric protein, flagellin, prepared from the flagella of this organism has been purified. It has a molecular weight of about 38,000 and contains in particular three methionine residues, but no cysteine, histidine or tryptophan. Flagellin was readily polymerized by treatment with ammonium sulphate to form linear polymers which under the electron microscope looked the same as the original flagella particles^1,2. These proteins were highly immunogenic in the adult rat; amounts of less than 1 µg, when injected in saline, gave rise to readily detectable amounts of antibody³. Tolerance to flagellin has been previously described in newborn⁴ but not in adult rats. Tolerance has now been achieved in adult rats by the injection of flagellin degraded by cyanogen bromide, a reagent which cleaved the polypeptide chain at methionine residues.