Humoral and cellular immune responses to the fimbriae of Porphyromonas gingivalis and their synthetic peptides.

Subcutaneous injection of fimbriae from Porphyromonas gingivalis strain 381 in Freund's incomplete adjuvant (FIA) resulted in an excellent serum anti-fimbrial immunoglobulin G (IgG) response in guinea-pigs and BALB/c mice. Administration of P. gingivalis fimbriae also elicited distinct cellular immune responses to the fimbriae in terms of ear lobe reaction in BALB/c but not in BALB/c nu/nu mice, and of skin reaction in guinea-pigs. When the guinea-pigs were given a semi-synthetic adjuvant GM-53--sodium beta-N-acetylglycosaminyl-(1-->4)-N-acetylmuramyl-L-alanyl-D-isogl utaminyl- (L)-stearoyl-(D)-meso-2, 6-diaminopimelic acid-(D)-amide-D-alanine--and fimbriae in FIA by subcutaneous injection, more enhanced production of serum anti-fimbrial IgG and stronger cellular immune responses were induced in the guinea-pigs than in those given fimbriae alone. Synthetic peptide FP381(202-221), which corresponds to the amino-acid residue numbers 202-221 based on the amino-acid sequence of fimbrilin from P. gingivalis strain 381, elicited humoral and cellular immune responses in guinea-pigs immunised with the fimbriae or FP381(202-221). Furthermore, subcutaneous administration of synthetic peptide FP381(61-80) with GM-53 induced lesser degrees of humoral and cellular immune responses in guinea-pigs than did FP381(202-221). However, when the fimbriae or FP381(61-80) were administered with bovine serum albumin (BSA), markedly elevated levels of specific anti-BSA antibody were seen in the serum of BALB/c mice. These results clearly indicated that fimbriae from P. gingivalis 381 and their oligopeptide segments induced humoral and cellular immune responses and exhibited immuno-adjuvant activities in guinea-pigs and BALB/c mice.