Let X be a compact Kähler manifold of dimension k and T be a positive closed current on X of bidimension (p, p) (1 ≤ p < k −1). We construct a continuous linear transform L p (T ) of T which is a positive closed current on X of bidegree (1, 1) which has the same Lelong numbers as T . We deduce from that construction self-intersection inequalities for positive closed currents of any bidegree.