Importance of Actinomyces and certain gram-negative anaerobic organisms in the transformation of lymphocytes from patients with periodontal disease.

Dental plaque deposits are known to be potent stimulants of lymphocyte transformation in patients with periodontal disease but not in normal subjects. Since plaque deposits consist mainly of whole bacteria, the cell walls of the most commonly found organisms in plaque were tested for their capacity to induce lymphocyte transformation. There was a direct correlation between the severity of peridontal disease and the amount of transformation induced by the cell walls of oral bacteria and by solubilized dental plaque. Cord blood leukocytes and lymphocytes from clinically normal people did not respond, which indicates that these stimulants are antigens rather than mitogens. Of the eleven bacteria tested, four members of the family Actinomycetaceae (Actinomyces viscosus, A. israelii, A. naeslundii, and Arachnia propionica), the related Propionibacterium acnes, and an anaerobic gram-negative anaerobic rod (27N). The high prevalence of the former organisms in the mature dental plaque that forms around the gingival crevice area and the potent efficacy with which they stimulate lymphocytes indicates that Actinomyces and certain gram-negative anaerobes may be important etiological agents in chronic periodontal inflammation in man.