There are many kits available. Most of them depends on fixing cells with 1-4% formaldehyde or paraformaldehyde followed by permeabilization (ex. Saponin). The famous one in my experience is the ebioscience intracellular staining kit. However, there many instances where these protocols/kits might not work due to nature of the antigen to be studied. For example, you need to know the localization of your antigen (cytoplasmic or nuclear?), does it exist in the soluble part or attached to the cell. Do you need to stain with cell surface at the same time or not..All these details are important sometimes.