3. Proof of an acute rejection in kidney transplant according to Banff-criteria: T-cell-mediated rejection as borderline, grade IA/B, IIA/B (no v-only), if one or more results are available as significant B-cell infiltrates CD20≥20 / high power field, glomerulitis, peritubular capillaritis or C4d positivity (with the exception of ABO-incompatible transplantations) as well as patients who have no T-cell-mediated acute rejection, but signs of acute humoral rejection (as listed above according to the criteria glomerulitis, peritubular capillaritis, C4d positivity) who have to be treated according to medical opinion of the physician with steroid therapy. The evidence of rejection can be performed by a protocol or indication biopsy.