Immunochemistry of S. kentucky (8.20); its relations with S. emek (8.20), S. virginia (8) and S. newport (6.8).

Immunochemical studies of S. kentucky showed that the strain has an identical polysaccharide with S. emek with which it shares the same "O" factors 8.20, and a common proteinic carrier of the polysaccharide. Absorptions of anti-S. kentucky sera with proteins from S. virginia ("O" factor 8) did not influence the homologous precipitations or agglutinations, nor the cross-reactions with S. emek. In contrast, the absorptions of the anti-S. Kentucky sera with proteins from S. newport (6.8) caused a conspicuous modification in the precipitations of S. emek proteins against the absorbed serum; this coincided with a drastic fall in the agglutinating titer for the heterologous S. emek strain while the homologous agglutination was unchanged. The results underlined the role of the specific proteins as agglutinogens and, in addition, sustain Kauffmann's recommendation for the preparation of the, empirically established, monofactor serum 20.