Immunological properties of Actinomyces viscosus: comparison of blastogenic and adjuvant activities

A water-soluble extract of Actinomyces viscosus was tested for its capacity to induce deoxyribonucleic acid synthesis in spleen cells from normal mice and to augment the in vitro antibody-forming cell (AFC) response to the T-cell-dependent antigen, sheep erythrocytes (SRBC) by T-cell-deficient adherent spleen cell monolayers from the same mice. Our results indicated that the water-soluble extract induced an in vitro blastogenic response, as assessed by tritiated thymidine incorporation into mouse spleen cells. The water-soluble extract also augmented the antibody response to SRBC. However, after fractionation of the water-soluble extract on Biogel P-300, not all of the fractions induced a blastogenic response and augmented an AFC response to SRBC. This difference in the ability of A. viscosus fractions to induce in vitro responses suggests that the water-soluble extract has multiple immunological properties. Chemical analysis of the water-soluble extract indicated an enrichment for amino acids and amino sugar common to peptidoglycan.