Oxazolone is a hapten that forms a complete antigen when bound to skin proteins. Through potent antigen presentation by skin dendritic cells (Langerhans cells), antigens on major histocompatibility complex (MHC) class II molecules are presented to CD4⁺ T cells. These T cells proliferate to form T-cell clones specific for hapten-modified self-peptides. Upon re-exposure to oxazolone, modified self-peptides are presented again on MHC class II molecules of dendritic cells. Memory T cells mount an immune response against these antigens by releasing cytokines, triggering a T cell-mediated delayed-type hypersensitivity reaction and thereby inducing intestinal inflammation.

SD rats (male, about 6 weeks old, weighing 180–220 g)

Modeling method: The ulcerative colitis model was established by skin sensitization with oxazolone followed by intracolonic enema of oxazolone for challenge.

Evaluation indicators: DAI score, CMDI score, colon index, colon length-to-width ratio, HE staining and HS score

DAI score, CMDI score

Colon index, colon length-to-width ratio

HE staining of colon tissue and HS score