1. When two chemically different carbohydrate derivatives are bound to the same protein, the newly formed antigens exhibit distinct immunological specificity.
2. When the same carbohydrate radical is conjugated with two chemically different and serologically distinct proteins both of the sugar-proteins thus formed acquire a common serological specificity.
3. The newly acquired specificity of the artificially prepared sugar-proteins is determined by the chemical constitution of the carbohydrate radical attached to the protein molecules. Simple differences in the molecular configuration of the two isomers,—glucose and galactose—suffice to orientate protein specificity when the corresponding glucosides of the two sugars are coupled to the same protein.
4. The unconjugated glucosides, although themselves not precipitable in immune serum, inhibit the reaction between the homologous sugar-protein and its specific antibody. The inhibition test is specific.
5. The sugar derivatives unattached to protein exhibit the properties of carbohydrate haptens; they are non-antigenic but specifically reactive, as shown by inhibition tests, with antibodies induced by proteins containing the homologous diazotized glucoside.
6. The specificity of artificially prepared sugar-proteins is discussed with reference to the chemo-immunological nature of the bacterial antigens containing complex sugars.
1. Type-specific antipneumococcus immunity has been induced in rabbits by immunization with antigen prepared by combining a specific derivative of the capsular polysaccharide of Type III Pneumococcus with globulin from horse serum. 2. Rabbits immunized with this antigen acquire active immunity against infection with virulent Type III pneumococci. 3. The sera of the immune rabbits contain type-specific antibodies which precipitate the Type III capsular polysaccharide, agglutinate Type III pneumococci, and specifically protect mice against Type III infection. 4. The experimental data are discussed with reference to: (1) the concurrence in the immune sera of type-specific antibodies for Pneumococcus and precipitins for horse globulin; (2) the determining influence of the capsular polysaccharide on the specificity of the antigen as a whole; (3) the unity of the type-specific precipitins, agglutinins, and protective antibodies induced by a single component of the pneumococcus in chemical union with an unrelated, animal protein.
Polysaccharides derived from type-specific Friedländer bacilli cause inhibition of the multiplication of mumps virus in the allantoic sac of the chick embryo. As little as 5 µg. of polysaccharide is effective as an inhibitor. Inhibition of multiplication is obtained when polysaccharide is injected as long as 4 days after inoculation of virus. Chemical studies have shown that the structural configurations of the polysaccharide responsible for specific serological activity are not identical with those which determine the inhibitory effect relative to mumps virus. The possible mechanisms of the inhibition of viral multiplication by means of polysaccharides are discussed.
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