Abstract
Summary
1. In studying the mechanism of the “capsular reaction” one of the first questions to be answered is whether or not the capsule swells when antibody is added. Data presented here indicate that it does not, using C. neoformans as a test organism. Exposure of washed, encapsulated C. neoformans to antibody results in a prominent clarification of capsular outline, but no increase in capsular size as determined by packed cell volume after centrifugation and by direct microscopic measurement. When cells with large capsules are employed, there is an apparent decrease in capsular size during the reaction with antibody. 2. If capsulated cells are not washed free of soluble capsular polysaccharide present in the cultural supernate, the soluble antigen coprecipitates when antibody is added. This may lead to the erroneous conclusion that there is an increase in capsular volume.
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