Isa 53:5 (NIVNKJV) "He was crushedwounded for our transgressions, He was bruised for our iniquities; the punishment that brought us The chastisement for our peace was on himupon Him, and And by his woundsHis stripes we are healed".
The 'Crown of Thorns' serves the same symbolic purpose as the 'stripes' does in the above quoted verse. This symbolic purpose is elaborated on in Isaiah chapter 58.