Hypersensitivity reactions in the small intestine. III. The effects of allograft rejection and of graft-versus-host disease on epithelial cell kinetics.

Allograft rejection of fetal intestine and graft-versus-host (GvH) disease have been used to study the effects of cell-mediated immune reactions on epithelial cell kinetics in mouse small intestine. In heterotopically transplanted isografts the cell production rate per crypt was similar to that in normally sited small intestine of the same age. However there was a six-fold increase in the rate of cell production per crypt during allograft rejection and a three-fold increase during GvH disease. Furthermore animals with GvH disease developed villous atrophy and had fewer crypts per villus that littermate controls. At the age of 19 days cell production per villus per hour was 97-5 in animals with GvH disease compared with 54-6 in controls. These results indicate that the pathological entity of 'partial villous atrophy' evolves in two distinct phases. Phase 1, a state of increased cell turnover with crypt hyperplasia but villi of normal length precedes the development of Phase 2, true villous atrophy.