Mast cells are known to express high levels of alpha4
integrins including alpha4beta7 and are found in increased numbers in mucosal
inflammation. Mast cell accumulation is particularly prominent in the intestine following
nematode infection. The adhesion molecule requirements for this process have not yet been defined. The role of alpha4 and
beta7 integrin chains in the intestinal mast cell
hyperplasia following
infection of rats with the nematode parasite Nippostrongylus brasiliensis was examined in this study. Rats were infected with N. brasiliensis larvae and treated with either anti-alpha4 (TA-2),
anti-beta7 or isotype-matched control
antibodies. The initial mast cell
hyperplasia in response to N. brasiliensis
infection was significantly inhibited by either anti-alpha4 or
anti-beta7 treatment. In contrast, the intestinal eosinophil response to N. brasiliensis
infection was not reduced at day 14 or day 16. Elevations in serum
IgE levels due to N. brasiliensis
infection were also not inhibited by anti-alpha4 or
anti-beta7 antibody treatment. Anti-alpha4 antibody but not
anti-beta7 antibody treatment also induced a small but significant decrease in the numbers of mast cells in tongue tissue. These data suggest a role for alpha4
integrins, in particular alpha4beta7, in the regulation of mast cell precursor migration to the intestine.