A New Method for the Production of Non-Specific Capsular Swelling of the Pneumococcus

Abstract

Summary

The experiments outlined indicate that pneumococcal polysaccharides combine with various proteins at pH 4.0 to form insoluble aggregates. This reaction is one of loose combination, since it can be reversed by readjusting the pH to 7.0. Non-specific capsular swelling of pneumococci can be produced also under these conditions, but, in addition, the protein-pneumococcus mixture at pH 4.0 must be relatively salt-free. It is felt that an altered state of the capsular gel is produced by the interaction of protein and carbohydrate. In the absence of ionized salts, the polysaccharide-protein gel becomes increasingly hydrophilic and therefore capable of enlarging to produce the “quellung” reaction. Both specific and the described acid-protein quellung can be produced in the absence of calcium in distinction to LofStrom's non-specific “quellung” phenomenon.

Grateful acknowledgment is made to Henry W. Scherp, Ph.D., Department of Bacteriology, University of Eochester School of Medicine and Dentistry, for supplying the polysaccharide preparations and eosin azo-protein, and for many helpful criticisms and suggestions.