The Protein-Crystalloid Complex as an Antigenic Unit. 20

Abstract

It was implied in all classical theories of specific immunity that the alien protein molecule functions as a single antigenic unit, stimulating the production of a single antiprotein substance or function. Within the last decade, however, this early theory has been challenged, several European theorists denying the assumed antigenic unity and postulating that the protein molecule is little more than an immunologically inert mechanical “carrier” of potentially antigenic superficial crystalloids. Each of these superficial “determinants,” “coefficients,” or “unit characteristics,” is pictured as functioning as a practically independent antigenic unit. There are numerous variants of this theory, differing mainly in the postulated degree of independence or interdependence of the sub-colloidal specificity determinants.

This concept is an apparently logical deduction from the “Land-steiner phenomenon,” the well-confirmed fact that immunochemically non-related proteins are more or less homologized if conjugated with the same non-antigenic crystalloid. The resulting antiserums apparently have anti-crystalloid functions which can be specifically “absorbed” from such serums.

A critical examination of published data of this type, however, has suggested a possible source of logical error, or at least of a distortion of the logical perspective. Medvecky and Uhrovits, 1 for example, studied the relative specificities of artificial protein-benzoyl conjugates. Quantitative analyses of all wash waters and other waste products in a duplication of their technic suggest that the average colloid of their end-products must have been the “carrier” of no less than 150 to 200 attached benzoyl radicals. Such a mechanical burying of the protein under a unit crystalloid must have given antigenic conditions rarely if ever duplicated in nature. We have, therefore, modified the quantitative relationships of their technic so that our average end-product is the “carrier” of not more than 20 to 30 benzoyl radicals. Typical relative specificities of 3 such partially benzoylated antigens are shown in Table I.