Clinical Uses of Seromucoid Estimation.

THE seromucoid* fraction of the plasma proteins comprises a group of glycoproteins-i.e., protein-carbohydrate complexes-characterized by their solubility in certain protein precipitants (perchloric, sulphosalicylic and trichloracetic acids) and by being not readily precipitated by heat. This fraction, which normally contains about io% of the total proteit-bound carbohydrate of the plasma and accounts for between i% and 2% of the total plasma protein, may be estimated by precipitation from perchloric acid filtrates of serum by the addition of phosphotungstic acid, the protein or carbohydrate .content of the precipitate being then determined (Winzler, Devor,' Mehl and Smyth, 1948). From its solubility properties and method of estimation it would appear that the seromucoid fraction is essentially identical with the socalled 'polypeptides', 'peptones' or 'albumoses' extensively studied by earlier workers (Wolff, I92I; Hahn, 1921; Cristol, 1922; Goiffon and Spaey, 1934; Fiessinger, 1934; and others). Indeed, the presence in human serum of a heatstable protein fraction soluble in acid proteinprecipitating agents was recognized as long ago as I892 (Freund), and this fraction was subsequently studied by Zanetti (I897), Bywaters (I906, I909), Rimington (1940) and others. An excellent historical account is given by Sonnet (1956). Variations-usually increases-in the plasma concentration of seromucoid are found in many conditions. The purpose of this brief review is to outline the principal diagnostic uses to which the estimation of seromucoid has been applied. No attempt is made to present an exhaustive account of the numerous clinical and other studies that have been made. Greenspan