Many Bacterial Species are Mitogenic for Human Blood B Lymphocytes

Abstract

Bacterial species [30] were tested for their ability to stimulate increased DNA synthesis in human blood lymphocytes. A definite stimulation was obtained with 18 bacterial species. For 3 of these species 10 different strains of each were tested, and all increased DNA synthesis. The maximum response was after 3-4 days of culture, suggesting a mitogenic effect. This was confirmed by the induction of polyclonal antibody [Ab] production shown by a plaque assay, which was positive for 9 of 11 species tested. Most bacterial species increased the DNA synthesis in B[bone marrow-derived]lymphocyte-enriched and unseparated lymphocytes but had negligible activity on T[thymus-derived] lymphocyte-enriched cultures. Among bacteria with a mitogenic effect and ability to induce polyclonal Ab production are Staphylococcus aureus strain Cowan I with a high content of protein A and many common human pathogens such as Haemophilus influenzae, Mycobacterium tuberculosis, Neisseria gonorrhoeae, Streptococcus group A and S. pneumoniae.