Comparative Immune Diffusion at Gelatin-Agar Interfaces: A Presumptive Test for Protein and Acidic Polysaccharide Antigens

[摘要] Analysis of a range of antigens by comparative immune diffusion, from wells located at the interface between gels containing 0.75% agar and 3% gelatin respectively, suggests that the formation of immune precipitates in gelatin is selective and restricted to protein and acidic polysaccharide antigens while immune precipitation in agar is not selective and not restricted to any class of antigens.The antigens examined included ferritin, dextran, bacterial polysaccharides, bacterial toxins, snake toxins and tobacco mosaic virus. Tobacco mosaic virus and its protein were the only protein antigens found to behave atypically by not producing bands in gelatin although bands were formed in agar.The mechanism of the selective nature of immune precipitation in gelatin was investigated. Methylation or acetylation of gelatin had no effect on the phenomenon but hydrolysis with pronase destroyed the ability of gelatin to interfere with immune precipitation.The effect of temperature was critical. At 37°C gelatin did not interfere with immune precipitation in gel diffusion or quantitative precipitin reactions with antigen-antibody systems inhibited by gelatin in the gel state at 2°C.In the gel state, gelatin is postulated to combine reversibly with antibody and antigen molecules. The outcome of competition between these nonspecific interactions and the antigen-antibody reaction is thought to determine whether or not immune precipitation will occur in gelatin gels.

[学科分类] 生物科学（综合）