CD4+ Lymphocytes Response to Streptococcus mutans GLU and PAc Peptides

Streptococcus mutans is the principal etiologic agent in dental caries. The PAc protein and the glucosiltransferases (GTF's) are virulence factors of this microorganism, and have been related to its physiopathogenia and studied as potential vaccine antigens. This bacteria induces an specific immune response, which has been better studied from its humoral than its cellular point of view. Experimental animal mocels had reported that synthetic peptides GTF-I (1301-1322) from the GLU region of the GTF's and PAc (365-377)have T and B epitopes, induce production of seric antibodies in saliva and diminish the presence of caries. Objectives: To observe if synthetic peptides have the capacity of activating CD4+ cells in peripheral blood taken from naturally sensitized humans, identify the type of response and establish the relation with the disease presence. Methods: Proliferation assays specific-antigen on pheripheral blood mononuclear cells (PBMCs)with the synthetic peptides PAC and GLU in three groups of patients: with active caries, history of disease and free of caries; followed by detection of intracellylar cytokines (IFNg, IL-13)by flow cytometry. Results: Peptides PAc and GLU are capable of activating an average of 5.9% of the total CD4+ cells. 0.3% of the cells activated by GLU and 0.8% by PAc produced IL-13; both peptides activated the production of IFNg in 1,86% of the cells. Three difeferent profyles of cytokines were identified. TH0, TH1, TH2, besides a non responsive cell type group. No differences were encontered in the subpopulation of activated CD4+ cells between groups. Conclusions: Human CD4+ cells activated in response to PAc and GLU in similar conditions in all the individuals, the activation does not depend of disease status; there are not differences in the production of cytokines. The evaluated peptides would not be good vaccine-antigen candidates in humans.