1990 Volume 53 Issue 1 Pages 47-62
Outer membrane proteins (OMP) of Bacteroides endodontalis HG 370 (=ATCC 35406) were prepared from the cell envelope fraction of the organism. The cell envelope that had been obtained by sonication of the whole cells for 20 minutes was extracted in lithium dodecyl sulfate, followed by partial purification by successive chromatography with Sephacryl S-200HR, and DEAE-Sepharose Fast Flow. On the other hand, B. endodontalis lipopolysaccharides (LPS) were prepared by hot phenol/water extraction. Two OMP fractions, OMP-I and OMP-II, were obtained, and their immunochemical properties and induction of specific antibodies were investigated :
1. The OMP-I preparation consisted mainly of a protein with an apparent molecular weight of 31,000 (31K), while the OMP-II preparation was composed of 15.5K, 27K and 44K proteins as revealed by SDS polyacrylamide gel electrophoretic analysis.
2. Immunodiffusion tests revealed that anti-OMP-I serum formed three precipitin bands against the homologous OMP-I and against OMP-II, respectively. One of the precipitin bands of the OMPs produced a fused precipitin band. On the other hand, anti-OMP-II serum formed two precipitin bands against OMP-II and only one precipitin band against OMP-I.
3. OMP-I was found to exhibit significant porin activity, i. e. the ability to form hydrophilic diffusion pores by incorporation into the artificial liposome membrane. However, the liposomes containing heat-denatured OMP-I were scarcely active.
4. Spontaneous and antigen-specific IgM, IgG, and IgA-secreting cells (SFC) enzymatically dissociated into single cell suspensions from chronically inflamed periapical tissues, and were enumerated by ELISPOT assay. In patients with radicular cysts or dental granulomas, the major isotype of spontaneous SFC was IgG. In radicular cysts, the OMP-II -specific IgG-SFC represented 0.006%〜0.03% of spontaneous IgG-SFC. No antigen-specific IgA- or IgM-SFC was observed. However, these mononuclear cells did not contain lymphoid cells producing antibody to antigen such as OMP-I or B. endodontalis LPS.
