Journal of Dental Research, Vol 64, 431-436, Copyright © 1985 by International & American Associations for Dental Research Online Journals
Effects of a Fusobacterium nucleatum extract on immunoregulation in mice
H. Yoshie, T. Mitsuma, K. Kozima and K. Hara
The purpose of this study was to examine the effect of an extract of
Fusobacterium nucleatum on humoral and cell-mediated immunity and phagocyte
functions in mice. The extract was obtained from the heat-inactivated
supernatant of sonicated F. nucleatum. Mouse splenocytes were cultured with
sheep red blood cells (SRBC), and antibody formation was assayed by
counting the plaque-forming cells (PFC). After C3H mouse skin was grafted
onto the BALB/c mouse, cytotoxicity of BALB/c mouse splenocytes to L-cells
was enumerated, T- and B-cell blastogenesis was determined by the uptake of
3H-thymidine. In vivo phagocyte functions were measured using carbon
clearance test, bactericidal, and acid phosphatase activity assays. The
number of SRBC-specific and non-specific PFC in splenocytes stimulated with
the extract increased 2.5-8.7-fold over that of unstimulated splenocytes.
Cytotoxicity of splenocytes from the extract-injected mice decreased in a
dose-dependent fashion at 12 days after grafting. T-cell mitogenicity of
the extract was observed. The carbon clearance rate was reduced, and
bactericidal and acid phosphatase activities were elevated by the extract
injection of the mice. In conclusion, F. nucleatum extract has an adjuvant
effect on humoral immunity, and a suppressive effect on cell-mediated
immunity and activated phagocyte functions.
