It is proposed that the development of periodontal disease is associated with rising levels of serum and gingival crevice fluid (GCF) IgG antibodies to specific organisms, while treatment of periodontal disease is associated with a decline in specific IgG antibodies. This study examined the immune response to Bacteroides gingivalis, a suspected periodontal pathogen, in serum and GCF of patients with adult Periodontitis. Three groups of subjects were studied: (1) patients with untreated adult Periodontitis, (2) patients with treated adult Periodontitis, and (3) patients with gingivitis (controls). An enzyme‐linked immunosorbent assay was employed using whole formalinized B. gingivalis (ATCC 33277) as antigen. Results showed that the untreated adult Periodontitis patients had a humoral immune response to B. gingivalis, producing significantly higher serum levels of IgG antibody to that organism than did patients with treated adult Periodontitis (p ≤ 0.01) or gingivitis (p ≤ 0.005). The untreated patients also demonstrated a local immune response to B. gingivalis in that their GCF levels of IgG antibody to that organism were also significantly higher than levels in treated adult Periodontitis patients (p ≤ 0.005) and gingivitis patients (p ≤ 0.001). These results are consistent with reports by other investigators. However, ratios of GCF antibody to serum antibody in the untreated adult Periodontitis group were not significantly higher than ratios in the other two groups. This suggests that the local immune response to B. gingivalis, as measured by GCF levels of IgG antibody to that organism, may be the result of leakage of serum into the GCF and not a site‐specific response to infection. Additionally, we have described a Western blot technique which showed that IgG antibody in serum recognizes several antigens sites of B. gingivalis.

A diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A) binding subunit has been resolved from a high molecular weight (640,000) multiprotein form of DNA polymerase alpha [deoxynucleoside triphosphate:DNA nucleotidyltransferase (DNA-directed), EC 2.7.7.7] from HeLa cells [DNA polymerase alpha 2 of Lamothe, P., Baril, B., Chi, A., Lee, L. & Baril, E. (1981) Proc. Natl. Acad. Sci. USA 78, 4723-4727]. The Ap4A binding activity copurifies with the DNA polymerizing activity during the course of purification. Hydrophobic chromatography on butylagarose resolves the Ap4A binding activity from the DNA polymerase. The Ap4A binding activity is protein in nature since the binding of Ap4A is abolished by treatment of the isolated binding activity with proteinase K but is insensitive to treatment with DNase or RNase. The molecular weight of the Ap4A binding protein, as determined by polyacrylamide gel electrophoresis under nondenaturing conditions or by NaDodSO4/polyacrylamide gel electrophoresis after photoaffinity labeling of the protein with [32P]Ap4A is 92,000 or 47,000. The binding activity of this protein is highly specific for Ap4A.

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