[Stimulation of nonspecific immune defense and antibody synthesis with zymosan]

A local sterile inflammation was induced in mice of different inbred strains by means of an i.p. injection of zymosan, a water-insoluble polysaccharide of the cell wall of Saccharomyces cerevisiae. This resulted in a strong enhancement of the unspecific resistance against infections with a LD 90 of gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Bordetella bronchiseptica). Furthermore, the treatment with zymosan before or after an immunization with sheep erythrocytes (SE) resulted in a significantly increased specific IgM and IgG primary response in the spleen. However, it was particularly striking that the number of plaque-forming cells against SE was very drastically enhanced in non-immunized mice, in particular cases even up to more than 70 times over the background. Consequently, zymosan possesses immunomodulating effects both on the unspecific resistance and on immune reactions. These results are discussed in relation to the Lyt+-B-cells and an acute phase reaction of B-cells.