The Immunological Specificity of Chemically Altered Proteins

Abstract

The immunological specificity of protein antigens has interesting aspects from the chemical viewpoint. Protein specificity appears to be closely associated with, and dependent on, chemical differences in the protein molecules. In most instances these differences are such that it is not possible to distinguish between similar proteins of different species by the usual methods of chemical investigation, but there are instances in which such a differentiation is possible by chemical or physical as well as by immunological tests. The differences which are responsible for serological specificity may not necessarily involve variations in the amount of certain special amino acids or even of free groups such as amino or carboxyl groups, but may be due merely to differences in the structural or spatial arrangement of certain groupings. A fundamental difference between antigenicity and specificity is indicated by the more recent work on complex antigens and haptens.There are several methods applicable to the study of the relationship between immunological specificity and the chemical properties of antigens; (a) alterations in the chemical constitution of the protein can be effected by various chemical processes such as oxidation, iodination, nitration, esterification, etc. (Obermayer and Pick (1), Landsteiner (2)), (b) a comparison can be made of the immunological properties of closely related vegetable proteins (Wells and Osborne (3)) or animal proteins (cf. review by Wells (4) pp. 68-74), and (c) compounds of well-defined chemical nature can be attached to the protein molecule (Landsteiner (5)). Each of these methods has a special

The immunological properties of alkali-treated proteins

“…of 7 % NH40H solution, and treated with N/10 iodine solution until there was a considerable excess of iodine [cf. Wormall, 1930]. The iodinated proteins were precipitated by the addition of 10% acetic acid to give maximum precipitation, and the precipitated protein was removed by centrifuging.…”

“…The products of this reaction react immunologically like proteins nitrated by a method which does not involve treatment with strong acid, viz. the tetranitromethane method [Wormall, 1930] Immunisation.…”

“…Iodination of proteins leads to no loss of antigenic power, but the original species specificity is lost and a new specificity acquired [Obermayer and Pick, 1906], this new specificity being characteristic for the 3: 5-dihalogenated tyrosine grouping [Wormall, 1930]. Iodination of the alkali-treated proteins used in this work led to some regeneration of antigenic function (cf .…”

“…For the latter purpose, it was considered that iodination of the alkali-treated proteins would be most suitable, since iodination can be effected in neutral or faintly alkaline solution, and, although it replaces the original species specificity of serum proteins by a specificity determined principally by the 3: 5-diiodotyrosine groupings [Wormall, 1930], iodination does not lead to any appreciable loss of antigenic properties.…”

Thyroidal Action of Synthetic Thyroprotein

“…Although one would expect to obtain eventually a protein sensitization of animals injected with a material of this nature, no untoward reactions have been noted following its daily injection in mice over a period of several weeks. In this connection it is interesting to note that Wormall (34) reported that proteins lose their antigenic specificity when iodinated and acquire a new specificity for iodoprotein.…”