Expression of TNFR2 in tumor cells from ATL patients. (A) A biopsied lymph node shows numerous atypical large lymphoid cells positive for TNFR2. (B) In this skin lesion, infiltrating tumor cells were positive for TNFR2, whereas epithelial cells (arrow) were negative. (A-B) Original magnification ×400, immunostaining with polyclonal antibodies against TNFR2.