Inhibition of hemagglutinating antibodies by natural and synthetic haptens
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Landsteiner's technique of specific serological inhibition has proved to be a valuable source of information as to chemical structure of the A, B and H antigens. The same method has given certain information also in the field of Rh chemistry. With this background in mind, the present study has been undertaken to investigate further the chemical structures of the blood group antigens, and to study the differences in specificity that exist between animal antibodies and the plant hemagglutinins (lectins) that are active for the same blood group. The investigation included the blood group antigens A, B, 0, M, N, D, C, E, c, and e. The following lectins were used in addition to the type specific antisera: Phaseolus lunatus limensis (Sieva Lima bean), (Anti-A), Dolichos biflorus (anti-a1), Vicia graminea (anti-N), Bauhinia purpurea (anti-N). The various groups of compounds tested for inhibition include: 1. Amino acids and amines 2. Vitamins, e.g., B and C. 3. Phenols and naphthols 4. Purines, pyrimidines, nucleosides and a nucleotide 5. Conjugated monosaccharides The method of the inhibition reaction used in this work was the usual one. The conclusions from inhibition studies with amino acids were strengthened by the results of histidase treatment of the erythrocytes. The following paragraph will give a very brief outline of the observations made. In contrast to the large number of experiments concerning the carbohydrate portion of the blood group substances, amino acids have attracted so far very little attention, although they have been known to be components or isolated blood antigens for a long time. or the thirty amino acids and amines tried, three can inhibit Rh antibodies, namely, L-histidine, L-cysteine and L-lysine. Inhibition by L-lysine seems to be rather non-specific. Histidase (specific substrate being L-histidine) treatment or the erythrocytes shows that the enzyme can specifically destroy the Rh antigens, leaving A, B, O, M and N agglutinating activities unimpaired. Thus, the role of L-histidine in the chemical structure of the Rh antigens is confirmed. The experiments with purine and pyrimidine haptens show that a number of the anti-Rh sera are completely inhibited by such low molecular compounds as caffeine, theophylline and theobromine. The inhibition reaction with these compounds points to the importance or a purine structure in the adjacent parts or the erythrocytes to which the blood group antigens are attached. Certain vitamins like thiamine hydrochloride and sodium ascorbate are capable of inhibiting all serological reactions in the Rh system. Thiamine shows a maximum inhibitory activity on anti-E and may be related to the E antigen. In the experiments with phenols the relative number and positions or the hydroxyl groups in the benzene ring seem to be important. The use of phenols in the Rh system reTeals the increased inhibitory power of dihydroxy phenols over mono- and tri-hydroxy phenols [TRUNCATED]
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