Characterization of protective activity in human sera against infection with Klebsiella ozaenae

Abstract

Biological and immunological properties of serum factor that offers a resistance to the infection by K. ozaenae was studied with sera from healthy human subjects and a patient suffering from pneumonia caused by K. ozaenae. Eighty four out of 100 sera obtained from healthy human subjects offered passive protection against a challenge infection with strain KO-2 of K. ozaenae in mice. Also sera obtained from pneumonia, patient infected with K. ozaenae showed quantitative passive protective activities in accordance with bacterial agglutination titers.Passive protective activity of the patient's serum was abolished by the absorption with either whole cells and cell surface polysaccharide of strain KO-2, or anti-human IgG, IgA and IgM serum. Serum contents of IgG, IgA and IgM were measured after an absorption with cell surface polysaccharide, but the reduction of specific immunoglobulin was not observed and the reduction percent of each immunoglobulin was only 10 to 14.These results indicate that protective factor in human serum against infection with K. ozaenae would be antibodies against cell surface polysaccharide containing in these immunoglobulins.Furthermore, the specificity of the passive protective activity of each surface polysaccharide of K. ozaenae or K. pneumoniae was demonstrated from the experiment employing the above patient serum and rabbit anti K-9 strain of K. pneumoniae serum.