T‐cell‐receptor gene usage of Actinobacillus actinomycetemcomitans‐ reactive periodontal CD4 + T cells from localized juvenile periodontitis patients and human peripheral blood leukocyte‐reconstituted NOD/SCID mice

We investigated the variable Vα and Vβ gene usage of Actinobacillus actinomycetemcomitans ‐reactive periodontal CD4 + T cell receptors (TCR) from: (i) four A. actinomycetemcomitan s‐infected localized juvenile periodontitis (LJP) patients, (ii) four groups of A. actinomycetemcomitans ‐inoculated NOD/SCID mice engrafted with individual LJP‐derived HuPBL and (iii) HuPBL samples of four LJP patients and two healthy control subjects, by quantitative PCR analyses. The results show that: (i) the majority of the TCR genes (82.5% of Vα and 91.1% of Vβ) used by periodontal CD4 + T cells in A. actinomycetemcomitans ‐inoculated HuPBL‐engrafted NOD/SCID mice overlap with those used by local periodontal T cells in LJP patients, (ii) although A. actinomycetemcomitans ‐reactive periodontal CD4 + TCR repertoire is relatively widespread, there are a few dominant genes shared by the LJP patients, suggesting a limited number of antigens or epitopes commonly recognized and (iii) A. actinomycetemcomitans likely lacks superantigenic characteristics. These results suggest A. actinomycetemcomitans ‐associated human CD4 + T cell repertoire established in HuPBL‐NOD/SCID mice provides a useful approach to study specific aspects of immune–parasite interactions in the periodontium.