In-vitro evaluation in man of immunostimulation by subfractions of Actinomyces viscosus

Abstract

Actinomyces viscosus was fractionated into cell wall (PEL) and intracellular supernatant (SUP) fractions following ultrasonication. In vitro lymphocyte transformation induced by each fraction was assessed using the lymphocytes obtained from subjects with minimal periodontal disease. In kinetic experiments, a detectable blastogenic response to both fractions was measured by the fourth day, with a peak at day 7. Nuclease treatment enhanced the immunostimulatory activity of the PEL fraction 5.5-fold over untreated PEL; it had no effect on the activity of SUP. Although pronase treatment had no effect on the PEL fractions, it abrogated the ability of SUP to activate lymphocytes. Fractions of nuclease-treated and untreated SUP were batch-eluted from DEAE-sepharose columns with increasing concentrations of NaCl, producing 3 major stimulatory subfractions which accounted for 75 per cent of the activity of unfractionated SUP. Comparisons of lymphocyte responses to the DEAE-fractionated SUP indicated that not all individuals responded equally to each subfraction. As there was a differential responsiveness to the various antigenic components, detailed evaluation of the antigens of A. viscosus is warranted to define differences in antigen responsiveness in individuals with differing severities of periodontal disease.