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,**2
*
Cell Biology and Aging Section (151E), Department of Veterans Affairs Medical Center, San Francisco, CA 94121;
Department of Anatomy, University of California, San Francisco, CA; and
**
Centre International de Recherche Daniel Carasso, 92350, Le Plessis-Robinson, France.
2To whom correspondence should be addressed. E-mail: coach{at}itsa.ucsf.edu.
The adjuvant effect of kefir fermented milk on the mucosal and systemic
immune systems was examined in young (6 mo old) and old (26 mo old)
rats. Kefir-fed rats consisted of young or old rats consuming
kefir-fermented milk ad libitum on a daily basis in addition to the
standard diet, for 28 d. Control rats consumed only the standard
diet. The rats were immunized intraduodenally with cholera toxin (CT)
on d 7 and 21 and killed on d 28. The nonspecific serum immunoglobulin
(Ig)A titers in kefir-fed and control rats did not differ in either
age group. The serum anti-CT IgA antibody concentrations were
significantly higher in the kefir-fed young rats compared with
their age-matched controls (+86%, P
0.05).
This difference was associated with enhanced in vitro antibody
secretion by cultured lymphocytes isolated from the Peyers patches
and the intestinal lamina propria (+180%, P
0.05). These enhanced responses were found only in the young rats.
However, the nonspecific serum IgG titer was higher (>120%,
P
0.05) and the anti-CT IgG titer was lower
(-80%, P
0.05), in both young and old
kefir-fed rats compared with their respective controls.
Nevertheless, these results demonstrate that a kefir-supplemented
diet affects the intestinal mucosal and systemic immune responses to
intraduodenal CT differently in young and old rats. Most importantly,
our data suggest that orally administered kefir enhances the specific
intestinal mucosal immune response against CT in young adult, but not
in senescent rats.
KEY WORDS: kefir intestinal immunity cholera toxin aging rats