english: But our bodies have a natural immune-defense system: cells that reside in the bloodstream and pick out things that don't belong, so that it can destroy or eliminate them.
non_english: Međutim, naše telo ima prirodni imuni sistem za obranu, ćelije koje postoje u krvotoku i prepoznaju šta tu ne pripada, tako da to mogu da unište ili uklone.