This antibody is specific to 160 kDa protein known as Factor XIII-A. Factor XIII is a β-globulin found in plasma and is composed of two subunits, Factor XIII-A and Factor XIII-B. Factor XIII-A is the catalytic subunit and is a dimer of M.W. 160 kDa. Factor XIII is a dermal dendrocyte marker and v variable reaction with these types of tumors.