Figure 5.

Granulocyte-macrophage colony-stimulating factor–activated monocytes (GMaM) induce Foxp3⁺T cells in dextran sulfate sodium (DSS)-induced colitis, and T cells mediate the beneficial effect of GMaM. (A) Regulatory T cells (Treg) were stained in wild-type (WT) mice treated with DSS (red frames) and control WT mice using a monoclonal antibody raised against Foxp3. Examples of colonic lymph follicles harboring Treg are shown for each treatment group (scale bar: 50 μm). (B) The number of Foxp3⁺ cells in lymph follicles was quantified and is displayed as mean ± standard error of the mean (SEM) of positive cells per mm² (n = 8–12). (C) Chronic colitis was induced by repeated oral administration of DSS in Rag1^−/− mice. Untreated Rag1^−/− mice that received only plain water served as controls. One day before the start of the third treatment cycle, mice received control monocytes, GMaM, or as a vehicle control phosphate-buffered saline alone, intravenously by the tail vein. Body weight of Rag1^−/− mice was monitored and is shown as the percentage of weight change of two independent experiments (n = 6 per treatment group). (D) Colons were removed, and the colon lengths were measured for each treatment group. Graphs show the mean ± SEM. Statistical significance was determined by unpaired student’s t-test. *P < .05; ***P < .001.