712 THE CHEMISTRY OF ANTIGENS 



the proteins from blood serum with a view to determining their antigenic activity. 

 He separated a globulin and an albumin fraction, and obtained specific precipitins 

 for the globulin but not for the albumin. The next year Le Blanc' separated both 

 euglobulin and pseudoglobulin, as well as albumin, from beef serum, and found that 

 all three fractions were immunologically specific, each when injected into rabbits pro- 

 ducing precipitins for itself only. In his confirmation of Le Blanc's work Hunter' 

 decided that the specificity of these proteins was relative, or quantitative, rather than 

 absolute, or qualitative. Dale and Hartley,^ using the delicate uterine-strip method 

 of demonstrating anaphylaxis instead of the precipitin reaction, concluded that all 

 three of these proteins were independent of one another antigenically, and that the 

 apparent overlapping was due to their incomplete separation. 



Still another antigen was demonstrated in serum when Doerr and Berger^ ob- 

 tained a second albumin fraction. They considered all four of these serum proteins 

 to be distinct from one another immunologically. Hektoen and Welker^ found these 

 serum proteins to be not only distinct but species specific as well. 



To the roster of antigenic plasma constituents already discussed we may add 

 fibrinogen, which Bauer and EngeP found to be antigenically independent of the 

 serum proteins, and seromucoid. In a recent study of the plasma fibrinogen from a 

 number of mammals and fowls Hektoen and Welker^ found that whereas, as an 

 antigen, it is distinct from the serum proteins, a strict species specificity seems to be 

 lacking. There even seems to be a relation between the mammalian fibrinogens and 

 those of birds. The anaphylactogenic properties of the seromucoids of various 

 animals have been studied by Lewis and Wells.^ They are apparently species specific. 



In the formed elements of the blood other antigens have been demonstrated. 

 Bennett and Schmidt' separated a globulin from laked red blood cells, which, injected 

 into rabbits, produced agglutinins and hemolysins for the homologous cells as well as 

 precipitins for the globulin itself. 



Antisera containing precipitins for hemoglobin have been obtained by Hektoen 

 and Schulhof'" by injecting rabbits with either crystallized hemoglobin or an aqueous 

 extract of red blood cells from which all proteins except hemoglobin have been re- 

 moved by treatment with aluminum cream. They split hemoglobin into globin and 

 hematin, and showed that the globin-free hematin solution contained the antigen, 

 whereas the precipitated globin was inactive. Antisera prepared with the hematin 

 solution were as specific as those obtained with the original extracts, containing pre- 



^ Le Blanc, A.: La Cellule, i8, 335. 1901. 



^Hunter, A.: /. Physiol., 32,327. 1905. 



3 Dale, H. H., and Hartley, P.: Bioc/iem. J., 10, 408. 1916. 



1 Doerr, R., and Berger, W.: Zlsclir. f. Ilyg. 11. hifcktuniskrankh., 96, 191. 1922. 



5 Hektoen, L., and Welker, W. H.: /. Iiifccl. Dis., 35, 295. 1924. 



^ Bauer, J., and Engel, S. 'V.: Biochem. Zlschr., 42, 399. 1912. 



'Hektoen, L., and Welker, \V. H.: /. Lifecl. Dis., 40, 706. 1927. 



* Lewis, J. H., and Wells, H. G.: ibid., p. 316. 1927. 



9 Bennett, C. B., and Schmidt, C. L. A.: J . Iinniunol., 4, 29. 1919. 



'"Hektoen, L., and Scluilhof, K.: J. Inject. Dis., 31, 2,2. 1922. 



