Labeling of immune cell markers (CD4 + T cells, CD8 + T cells, CD11b + cells and CD11c + cells) as well as insulin and glucagon labeling showed no inflammatory cell infiltration around the islet cells with an intact structure of islet β-cells and α-cells in the pancreatic tissue of the PBS-treated mice, whereas, massive inflammatory cell infiltration occurred with the absence of islet β-cells and α-cells in the T1DM mice. The gene discussed is CD8A; the disease is type 1 diabetes mellitus.