Provided is a method of activating immune cells and/or an immune system response in a subject. The method may comprise administering to a subject an effective amount of a compound of Formula (I): or a prodrug, derivative, and/or salt thereof. In some embodiments, the method comprises contacting an immune cell with a compound of Formula (I) or a prodrug, derivative, and/or salt thereof. Also provided are compounds, compositions, and kits for activating immune cells and/or an immune system response in a subject.