Figure 4

Immunohistochemical detection of MRP3 with the M₃II-9 Mab in normal human liver and in livers from patients with bile duct obstruction. In normal human liver, generally low levels of MRP3 are detected, mainly at the bile ducts (a). The negative control Mab is shown in b. In the PFIC2 patient (c), and particularly in the patient with the Klatskin tumor (d), as well as in the PFIC1 patient (e), elevated MRP3 staining is observed within the proliferative bile duct epithelium, but no staining is seen in the hepatocytes. In contrast, unchanged levels of bile duct MRP3 but moderately to highly increased levels of MRP3 in the hepatocytes are observed in a patient with biliary atresia (f, Patient B) and in the hepatitis patient (g). The highest MRP3 levels are observed in the two PFIC3 patients (h, Patient D, and i, Patient E). In these livers, both bile ducts and almost all hepatocytes stain strongly positive for MRP3. For patient information see “Materials and Methods.”