CD38 and autoimmune disease: Specifically, both C15:0 and metformin significantly lowered: HLA-DR in the 3C system relevant to cardiovascular disease and chronic inflammation; MCP-1, CD40, and CD69 in the LPS cell system relevant to cardiovascular disease and chronic inflammation; CD38, CD40, CD69, and T cell proliferation in the SAg cell system relevant to autoimmune disease and chronic inflammation; IgG and TNFα in the BT system relevant to asthma, allergy, cancer, and autoimmunity; and VCAM-1 in the HDF3CGF system relevant to fibrosis and chronic inflammation.