IBD was induced by the injection of BALB/C CD4+ T cells into mice with severe combined immunodeficiency (SCID), and resultantly, the tissue level of GLP-1 in the colon was decreased approximately six and nine-fold compared to the SCID and BALB/C controls, likely due to destroyed or suppressed L-cells in the inflammatory state. This evidence concerns the gene CD4 and inflammatory bowel disease.