The purpose of this study was to compare the lymphoproliferative response to Actinobacillus actinomycetemcomitans (Aa) and to phytohemaglutinin (PHA) mitogen, in groups of patients with early-onset periodontitis (EOP, n = 9), adult periodontitis (AP, n = 20), and healthy controls without periodontal disease (n = 20). As antigens, a mixture of sonicated extracts of five isolates obtained from EOP patients, and sonicated extracts of Aa reference strains ATCC 29522, ATCC 29523, and FDC Y4 were used. No statistically significant difference was observed between the three groups as to the lymphoproliferative response to Aa. The use of previously heated and unheated Aa sonicated extracts demonstrated the existence of heat-labile factor or factors capable of depressing the specific lymphoproliferative response. This indicates the necessity of using a heated extract for a valid evaluation of lymphoproliferative response. As for the lymphoproliferative response to the PHA mitogen, no significant differences between groups were observed. This suggests that there was no induction of immunosuppression in the patients with periodontitis. In addition, in experiments with heated or unheated Aa extracts, the presence of heat-stable factor or factors capable of suppressing the PHA response was noticed. The presence of these factors could explain why no alteration of the cellular immune response was detected in the patients with periodontitis.
Immunity, cellular; Lymphocyte transformation; Periodontitis
