Histology of acute T cell-mediated rejection

(A) This periodic acid-Schiff (PAS)-stained, high-power microscopic image depicts an example of mild tubulitis identified in a patient with borderline acute T cell-mediated rejection. The arrow is pointing to a rare lymphocyte within the tubular epithelium (400x).
(B) Example of moderate tubulitis in a case of Banff IA acute T cell-mediated rejection. Thick arrows point to lymphocytes within the tubular epithelium (H&E, 400x).
(C) As the degree of cellular rejection increases, increased numbers of lymphocytes are seen within the tubular epithelium (short arrows). Severe tubulitis is seen in this example of Banff IB acute T cell-mediated rejection (PAS, 400x).
(D) Vascular rejection is defined by the presence of endothelialitis (attachment of lymphocytes to the vascular wall; arrowhead). In this case of Banff IIA rejection, the endothelialitis is mild (H&E, 400x).
(E) In this example of Banff IIB acute T cell-mediated rejection, the endothelialitis is severe (dashed arrow, H&E, 400x).