Figure 1

Activation-induced cytidine deaminase (AID) expression in the reactive germinal center and small lymphocytic lymphoma. (a) Predominant AID expression in the dark zone of a reactive germinal center, using the AID clone ZA001. (b) Small lymphocytic lymphoma on TMA with abundant AID-positive paraimmunoblasts. (c) Staining of the same case on whole tissue section showing a variable staining intensity in paraimmunoblasts, prolymphocytes and small lymphocytes. (d) Double staining for AID (cytoplasmic, brown) and Mib1 (nuclear, red) in a proliferation center showing proliferating and non-proliferating AID-positive cells.