Induction of Murine B Cell Proliferation and Immunoglobulin Synthesis by Some Bacterial Ribosomes

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Abstract
Ribosomal preparations from Klebsiella pneumoniae, Haemophilus influenzae, Streptococcus pyogenes, and Streptococcus pneumoniae were investigated with respect to their activating capacity towards murine lymphoid cells. The proliferation of BALB/c spleen cells was induced in a dose‐dependent fashion (from 1 to 100 μg/ml) by ribosomes of K. pneumoniae, H. influenzae, and S. pyogenes with a peak activity at 48 or 72 hr of culture. The majority of the blast cells induced by these ribosomal preparations were positive for surface‐immunoglobulin (S‐Ig) and negative for Thy 1.2. Furthermore, K. pneumoniae, H. influenzae, and S. pyogenes ribosomes induced the synthesis of IgM and some IgA. Cell proliferation and induction of IgM production were also demonstrated with the 3 ribosomal preparations using spleen cells from athymic nude (nu+/nu+) mice, Lyb‐5‐defective CBA/N spleen cells, B cell‐enriched and T cell‐depleted BALB/c spleen cell suspensions, as well as spleen cells from the Ips gene‐deficient C3H/HeJ strain. Cell culture supernatants contained specific anti‐ribosome IgM antibodies. Antibodies of other specificities (anti‐sheep erythrocytes) were also demonstrated in supernatants from K. pneumoniae‐stimulated cultures. Evidence against a possible role of contamination of K. pneumoniae and H. influenzae ribosomes by lipopolysaccharide‐ or lipid A‐associated proteins in this effect is discussed. Ribosomes from S. pneumoniae did not induce 3H‐thymidine incorporation nor Ig production. None of the 4 ribosomal preparations was found to stimulate T cell blastogenesis or to induce interleukin‐2 production by naive BALB/c spleen cells. Finally, ribosomes from H. influenzae, S. pyogenes, S. pneumoniae but not those of K. pneumoniae stimulated interleukin‐1 production by adherent spleen cells, from BALB/c mice.