Immunochemical Studies on Blood Groups

The finding that purified blood group A and B substances specifically precipitate the corresponding isoantibodies from the serum of normal and immunized individuals and that the amounts of these antibodies could be estimated by the microquantitative precipitin method (1) introduced by Heidelberger and MacPherson (2) has made it possible to apply the technics of quantitative immunochemistry to the characterization and study of these substances. For example, the relative purity of different preparations can be ascertained by comparing the amounts of each preparation required to precipitate a given amount of antibody. In addition, these procedures can be applied to study the stability of the blood group substances (for a review of the scope of quantitative immunochemical methods cf. references 3-5). The present study describes the use of these methods in comparing the relative purity of preparations of blood group A substance obtained by several methods from pools of hog stomachs together with a consideration of the pH stability range of the A substance. Data are also included on the chemical properties of the A substance, on the solubility of A anti-A specific precipitates, and on the magnitude of losses involved in washing specific precipitates.