Mapping of murine Th1 and Th2 helper T-cell epitopes on fimbriae from Porphyromonas gingivalis

Th1- and Th2-derived cytokine production in response to synthetic peptides of the fimbrial subunit protein (fimbrilin) from Porphyromonas gingivalis strain 381 was assessed in spleen mononuclear cells (MNC) of BALB/c mice (H-2d haplotype) immunised with the fimbrial protein antigen and adjuvant GM-53 in Freund's incomplete adjuvant (FIA). Sixty-seven sequential overlapping 10-mer peptides covering the complete 337 amino-acids (AA) protein of P. gingivalis fimbrilin were synthesised. Stimulation of spleen MNC in vitro with these 10-mer peptides resulted in the production of murine interleukin-2 (IL-2), gamma-interferon (IFN-gamma), IL-4, IL-5 and IL-6. Peptides 13 (AA 61-70), 24 (AA 116-125), 31 (AA 151-160) and 64 (AA 316-325) markedly induced IL-2 production. In particular, peptide 24 (DPLKIKRVHA), which contained I-Ad, I-Ed and I-Ak binding motifs, was the most potent stimulator of IL-2, IFN-gamma, IL-4, IL-5 and IL-6 production. Spleen MNC from C3H/HeN mice (H-2k) followed by BALB/c mice (H-2d) immunised with peptide 24 were high responders to peptide 24 in terms of both IFN-gamma and IL-4 production, whereas A/J mice (H-2a) and C57BL/6 mice (H-2b) were very low responders, P. gingivalis fimbriae evoked higher delayed-type hypersensitivity (DTH) reactions in B10.D2 (H-2d) and B10.BR (H-2k) mice followed by C57BL/10 (B10, H-2b) and B10.A (H-2a) and in guinea-pigs immunised with the fimbriae and GM-53 in FIA.(ABSTRACT TRUNCATED AT 250 WORDS)