Preliminary investigations have been made of the possibility of correlating changes in infrared absorption spectra of dried films of human blood sera with the occurrence of diseases of the hypersensitive state. These diseases, which may include rheumatic fever, rheumatoid arthritis, asthma, and many others, are thought to be due to an antigen-antibody reaction which might produce observable changes in the proteins of the circulatory system. Definite qualitative and quantitative changes have been observed comparing normal serum with various types of pathological serum. Absorption spectra of pure dried films of human albumin and gamma-globulin have also been determined and some of the changes in the blood spectra are possibly explainable on the basis of an altered A/G ratio, which is known to occur. However, all of the changes cannot be explained on this basis. The films of sera, albumin, and gamma-globulin were air-dried at room temperature on thin disks of KRS-5, and examined in the Perkin-Elmer spectrometer in the spectral range 850–1400 cm-1 (7 to 12 microns).
JOHN T. AGNEW, PHILIP LISAN, and M. JOHN BOYD, "The Use of Infrared Absorption Techniques in the Study of Hypersensitivity Diseases," J. Opt. Soc. Am. 42, 815-815 (1952)