IL-4- and IL-6-producing cells in human periodontal disease tissues were investigated using immunohistochemical and in situ hybridization techniques. Immunohistochemical analysis demonstrated the presence of IL-4-producing cells within the CD45RO+ subset and the percentage of IL-4+ cells was significantly higher in periodontal lesions than in gingivitis tissues (p < 0.01). The percentage of IL-6-producing memory cells was higher in periodontal lesions compared with gingivitis tissues, although it was not statistically significant (p > 0.05). A reverse tendency in IL-4- and IL-6-positive cells was observed in a few individual cases. No IL-4 mRNA could be detected using the in situ hybridization technique. However, high levels of IL-6 mRNA were present in clinically healthy tissues, with a further increase in both epithelium and connective tissues affected by gingivitis, although only the former was significant (p < 0.025). There was a significant decrease in IL-6 mRNA in both the connective tissue (p < 0.025) and epithelium (p < 0.01) in periodontitis tissues compared with levels in gingivitis tissues. However, the levels of IL-6 mRNA in periodontal tissues were high compared with those of IL-1 mRNA, which was used in this study as a positive control. These results suggest that Th2-type cells may accumulate in periodontal lesions.

The mouse abscess model has been used extensively to demonstrate protection after challenge with periodontopathic organisms. In the present study, an outer membrane (OM) preparation of P. gingivalis ATCC 33277 was used to immunize BALB/c mice prior to challenge with live P. gingivalis organisms. This OM preparation, particularly at the highest dose level of 100 μg/immunization, was able to induce high levels of specific antibody and subsequent protective immunity. Protection in all immunized mice was noted by the rapid healing of the primary lesions, a low incidence of secondary lesions, and, in the highest dose group, an absence of septicemia. Non‐immunized animals demonstrated a slower development as well as healing of primary lesions, with higher numbers and larger sizes of secondary lesions. Weight loss and behavior patterns such as hunched bodies, ruffled hair, and stiffness of the hind legs were particularly noted in this group. Depletion of CD4 T cells in mice prior to immunization with 100 μg P. gingivalis OM resulted in significantly depressed serum levels of anti‐P. gingivalis antibody and an increase in the physical signs of disease compared with both the immunized and control groups. Western blot analysis demonstrated three antigen bands (63.3, 50.1, and 45.1) recognized by all immunized groups and also the control non‐immunized group, although the latter recognition occurred only after challenge. A further antigen band of 36.1 kDa was recognized by sera from the highest dose group only. This study has demonstrated the ability of P. gingivalis OM to provide protection against challenge with live P. gingivalis organisms. The increased physical signs of disease seen in the CD4 depleted animals compared with the control group not only illustrate the protective role of serum antibody, but also suggest a possible role for T cell mechanisms in control of the lesion locally. The ability of specific OM antigens to provide similar protective immunity remains to be ascertained. J Periodontol 1995; 66:351–362.

A murine skin abscess model was used to study the immune response to an acute infection with Bacteroides forsythus. BALB/c mice were given subcutaneous injections of either viable or heat-killed B. forsythus, while a third sham-immunized control group received phosphate-buffered saline. Weights and lesion sizes were measured. Blood was collected from the heart and specific antibodies to B. forsythus measured by an ELISA. Swabs taken from the lesions and also from pooled blood were cultured anaerobically for viable B. forsythus. Viable B. forsythus-induced lesions reached maximum size at day 7. B. forsythus cells were recovered from lesions up to day 4 although none were cultured from blood samples. Heat-killed bacteria induced much smaller lesions. Serum antibody levels increased during the 9-day study period, being significantly higher in mice injected with viable compared with heat-killed B. forsythus. Antibody levels in sham control mice were significantly lower than those seen in the other two groups. These results showed that a subcutaneous injection of viable cells of B. forsythus elicited a pronounced abscess formation and induce higher levels of specific antibodies compared with that produced by an injection of dead bacteria. This suggests that, as with other periodontopathic organisms, this mouse model can be used to study the immune response to B. forsythus.

A significant positive correlation was found between the liquefaction time of human seminal coagula and bound sialic acid. There was also a similar relationship between bound sialic acid and the enzyme sialyl-transferase. This suggests that the degree of sialylation of the components of seminal coagulum are important in determining the liquefaction time of the coagulum. These results support previous findings. The coagulum is considered to be composed of glycoprotein-metal ion complexes, and the initial stage of liquefaction results from the reduction of these metal ions by L-ascorbic acid. The removal of hydrogen peroxide, generated by the oxidation of L-ascorbic acid, requires the presence of glutathione peroxidase and glutathione reductase. These enzymes have been identified in human seminal plasma and their possible physiological importance is discussed.