Pj. Baker et al., T-cell contributions to alveolar bone loss in response to oral infection with Porphyromonas gingivalis, ACT ODON SC, 59(4), 2001, pp. 222-225
We have previously shown that mice lacking CD4(+), but not CD8(+), T cells
lose less alveolar bone loss in response to oral infection with Porphyromon
as gingivalis than do immunocompetent mice of, the same genetic background,
indicating that CD4(+) T cells contribute to bone resorption. The CD4(+) a
nd CD8(+) T-cell knockouts were produced by targeted deletions of, respecti
vely, major histocompatibility complex II (MHCII) or beta (2)-microglobulin
(producing non-expression of MHCI). Because MHCI deletions can have other
effects in addition to those on T-cell selection, we wanted to confirm that
the lessened bone loss was truly an effect of the lack of T cells. Consequ
ently, we repeated our experiments with C57B1/6J-Tera mice that have a targ
eted deletion of the alpha chain of the T-cell receptor (Tera). Six weeks a
fter oral infection with P. gingivalis ATCC 53977 the total bone loss at bu
ccal maxillary sites was 0.28 turn in infected immunocompetent mice (P = 0.
002 compared with sham-infected mice), wheras in Tera knockouts the bone lo
ss was only 0.08 nim (P = 0.04 compared with shams). The T-cell-deficient m
ice thus lost 70% less bone after infection than did genetically matched im
munocompetent mice (P= 0.003). These experiments confirm that T cells, and
their responses to oral infection with P. gingivalis, help to push bone rem
odeling in the direction of net loss of bone.