Interleukin-1 (IL-1) is an important mediator of inflammation and has
been implicated in several forms of immunopathology. Here we have inve
stigated whether IL-1 plays a role in the enteropathy which occurs dur
ing a graft-versus-host reaction (GVHR) in mice. Non-irradiated (CBA x
BALB/c) F1 mice with GVHR had increased production of IL-1 and treatm
ent with rabbit anti-IL-1alpha antibodies abolished the crypt hyperpla
sia and significantly reduced the parallel increase in crypt length wh
ich occurs in the jejunum. Antibody treatment had no effect on the acc
ompanying increase in intraepithelial lymphocyte (IEL) counts or on th
e splenomegaly. Recombinant IL-1 itself produced villus atrophy, crypt
hyperplasia and increased IEL counts in normal mice and stimulated th
e proliferation of an intestinal epithelial cell line in vitro. We pro
pose that IL-1 plays an effector role in immunologically mediated ente
ropathy, either via direct effects on epithelial cells or secondary to
an action on other, stromal cells in the mucosa.