Diss Nikki final - TiHo Bibliothek elib - Tierärztliche Hochschule ...

Summary 106
tolerance towards harmless intestinal antigens is able to cause a persistent, inflammatory
overreaction of the GALT in the form of a Th 2 controlled hypersensitivity reaction
of type I.
Another aim of this study was to investigate the age-dependent expression of c-kit
and immunoglobuline E in the gastrointestinal tract of healthy dogs. For this purpose,
14 control dogs were divided into 3 different age-groups (group 1 = 1 month-1 year;
group 2 = 3-7 years; group 3 = 8-17 years). Although not statistically significant, there
was a clear decline of c-kit positive mast cells from group 1 to group 3. This could be
caused by a diminution of precursor cells in elderly individuals or could be due to a
general decrease of the proliferation rate in the intestinal mucosa at advanced age.
Considering the IgE expression, the data showed a significant increase of immunoglobulin
E from group 1 to group 2 and a decrease from group 2 to group 3. These
findings could be explained by the fact that the GALT of middle-aged dogs (group 2)
has been exposed to a much larger diversity and a greater amount of antigens than
the GALT of dogs of younger age (group 1). A decline of IgE positive cells at advanced
age (group 3) might be caused by an age-related diminution of B and T cell homing.
As a consequence, the amount of immunglobuline-secreting B cells in the lamina
propria of the gastrointestinal tract would be decreased as well.