Cell mediated immune responses to plaque antigens during experimental gingivitis in man

Abstract

The purpose of the present investigation was to evaluate the ability of antigens of human dental plaque microorganisms to stimulate peripheral blood lymphocytes (PBL) from humans during the development and recovery from experimental gingivitis. Eleven healthy dental students (22-36 years) participated in the study. At the start of the experiment, they exhibited clean teeth and clinically healthy gingivae. They then abstained from all oral hygiene measures for four weeks according to the model proposed by Loe et al. (1965). At the start, after 1, 2, 3 and 4 weeks of abolished oral hygiene and 2 weeks following reinstitution of oral hygiene, the oral conditions were assessed, using the criteria of the Plaque Index system (Loe & Silness 1964) and the Gingival Index system (Loe & Silness 1963). At each examination triplicate microcultures, each containing 2 x 105 viable PBL in .2 ml TC 199 with glutamine and antibiotics containing 10% fetal calf serum, were stimulated with four concentrations of sonicates from V. alcalescens, F. nucleatum, B. melaninogenicus, A. viscosus, A. naeslundii, S. sanguis and pooled dental plaque all obtained from a previously performed experimental gingivitis. The cultures were incubated for 78 hours at 37°C in 5% CO2. 3H-thymidine was added for the final 8 hours. Only A. viscosus was able to stimulate PBL to undergo blastogenesis during the development of experimental gingivitis. A. viscosus stimulated the PBL of 3 subjects after one week but all subjects after 2 weeks of abolished oral hygiene. The stimulation indices (SI) remained > 2.5 for the rest of the experimental period. Following 2 weeks of reinstituted oral hygiene, the SI reached preexperimental levels. These results suggest that A. viscosus is capable of inducing a specific cellular immune response during the development of experimental gingivitis and may be important as a causative plaque constituent. Further research is indicated to study this association.