ANTIBODY RESPONSE TO INFECTIONS WITH TYPE III AND THE RELATED TYPE VIII PNEUMOCOCCUS 1

Abstract

Many freshly isolated pneumococci of types III and VIII (Cooper, "Thomas Strain" or atypical type III of Sugg and Harris) gave significant degrees of cross agglutination in some horse antisera of related types. Sera of patients with lobar or bronchopneumonia associated with types III or VIII had homologous type-specific antibodies (agglutinins and mouse protection) similar to those following types I or II pneumonia. In type-Ill patients, antibodies were less frequent and of lower titer. Antibodies for the heterologous but related type were found frequently in sera of both types III and VIII patients. Absorption exps. showed that the major antibodies were for the patient''s organism and the minor antibodies were for the related type. When these organisms were found in conjunction with other pneumococci, they were oc casionally associated with true "mixed" infections, but type III more often had no significance, as judged by antibody formation.