At a recent meeting (Keystone Symposia on the immunology of viral infections)
Tim Mossman presented data suggesting that pregnancy is associated with Th2-
like responses, making the mother more susceptible to infections that are
normally cleared by a Th1 response.
This may go a little way in explaining why mothers don't reject the embryos.
A Th1-like response might be necessary for the cellular activation required
to reject a graft, and if the mothers are incapable of such a response,
'tolerance' results. Tolerance here may simply be a shift to a Th2-mediated
humoral response.
As with all immunology, it just can't be this simple :-)
--
Shiv Prasad shiv at lenti.med.umn.edu
Dept. of Microbiology pras0005 at student.tc.umn.edu
Univ. of Minnesota
