Specific in situ visualization of plasma cells producing antibodies against Porphyromonas gingivalis in gingival radicular cyst: application of the enzyme-labeled antigen method

J Histochem Cytochem. 2011 Jul;59(7):673-89. doi: 10.1369/0022155411408906. Epub 2011 Apr 27.


The enzyme-labeled antigen method was applied to visualize plasma cells producing antibodies to Porphyromonas gingivalis, flora of the human oral cavity. Antibodies to P. gingivalis have reportedly been detected in sera of patients with periodontitis. Biotinylated bacterial antigens, Ag53, and four gingipain domains (Arg-pro, Arg-hgp, Lys-pro, and Lys-hgp) were prepared by the cell-free protein synthesis system using the wheat germ extract. In paraformaldehyde-fixed frozen sections of rat lymph nodes experimentally immunized with Ag53-positive and Ag53-negative P. gingivalis, plasma cells were labeled with biotinylated Arg-hgp and Lys-hgp. Antibodies to Ag53 were detected only in the nodes immunized with Ag53-positive bacteria. In two of eight lesions of gingival radicular cyst with inflammatory infiltration, CD138-positive plasma cells in frozen sections were signalized for Arg-hgp and Lys-hgp. An absorption study using unlabeled antigens confirmed the specificity of staining. The AlphaScreen method identified the same-type antibodies in tissue extracts but not in sera. Antibodies to Ag53, Arg-pro, and Lys-pro were undetectable. In two cases, serum antibodies to Arg-hgp and Lys-hgp were AlphaScreen positive, whereas plasma cells were scarcely observed within the lesions. These findings indicate the validity of the enzyme-labeled antigen method. This is the very first application of this novel histochemical technique to human clinical samples.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Antibodies, Bacterial / blood*
  • Antigens, Bacterial / chemistry
  • Antigens, Bacterial / immunology
  • Antigens, Bacterial / metabolism*
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / immunology
  • Bacterial Proteins / metabolism*
  • Biotinylation
  • Endopeptidase K / chemistry*
  • Female
  • Genes, Bacterial
  • Humans
  • Immunization
  • Lymph Nodes / immunology
  • Lymph Nodes / virology
  • Male
  • Middle Aged
  • Plasma Cells / immunology*
  • Plasma Cells / microbiology
  • Plasma Cells / pathology
  • Porphyromonas gingivalis / genetics
  • Porphyromonas gingivalis / immunology*
  • Radicular Cyst / immunology*
  • Radicular Cyst / microbiology
  • Radicular Cyst / pathology
  • Rats
  • Rats, Sprague-Dawley
  • Sensitivity and Specificity


  • Antibodies, Bacterial
  • Antigens, Bacterial
  • Bacterial Proteins
  • Endopeptidase K