The influence of genetic variation on the splenic T cell cytokine and specific serum antibody responses to Porphyromonas gingivalis in mice

Background: T cell cytokine profiles in the spleens and anti-Porphyromonas gingivalis antibodies in the sera of P. gingivalis-immunized BALB/c (H-2(d) ), CBA/CaH (H-2(k)], C57BL6 (H-2(b)), and DBA/2J (H-2(d), C5 deficient) mic e were examined. Methods: Mice were immunized either by intraperitoneal injections of P. gin givalis outer membrane antigens and Freund's incomplete adjuvant weekly for 3 weeks or sham-immunized with PBS and adjuvant, followed by subcutaneous challenge with live organisms 1 week after the final immunization. Spleens were excised and blood samples collected by heart puncture at 0 and 7 days after challenge. Splenic CD4 and CD8 cells were stained for intracytoplasmi c interleukin (IL)-4, interferon (IF)-gamma, and IL-10 and levels of anti-P . gingivalis antibodies in the serum samples determined by ELISA. Results: Lesion sizes in immunized BALB/c mice remained stable for the 7-da y experimental period. Immunized CBA/CaH and C57BL6 mice exhibited large le sions at day 1 reducing by day 7 particularly in the latter strain. Lesions in immunized DBA/2J mice were still larger than the other strains at day 7 . With the exception of DBA/2J mice, sham-immunized mice demonstrated lesio ns which did not show signs of healing by day 7. T cell cytokine responses in sham-immunized mice at day 0 were low, increasing to a variable degree b y day 7 after challenge in the 4 strains. Immunized BALB/c mice demonstrate d intermediate T cell responses while generally exhibiting a stronger IFN-g amma response than IL-4 or IL-10. Immunized CBA/CaH and C57BL6 mice showed weak T cell cytokine responses while immunized DBA/2J displayed the stronge st T cell responses particularly in regard to IL-4 positive cells. Sham-imm unized mice had low levels of serum anti-P. gingivalis antibody levels at d ay 0 with levels increasing significantly by day 7 after challenge. Antibod y levels in immunized mice seemed to correlate with lesion sizes, immunized C57BL6 mice had the highest antibody levels followed by CBA/CaH, BALB/c wi th DBA/2J exhibiting low levels. The T cell and B cell antibody responses i n each strain appeared to exhibit an inverse relationship. Conclusions: This study has shown that genetic differences at the level of H-2 haplotype induce variations in the local and T and B cell responses to P. gingivalis antigens. The responses of DBA/2J mice which have the same ha plotype as BALB/c mice suggest that factors other than H-2 haplotype such a s the C5 deficiency may influence this immune response. The significance of the specific antibody and T cell responses and of their inverse relationsh ip to susceptibility to periodontal disease remains to be determined.