Figure 1.

(A) Double labelling immunohistochemistry and in situ hybridisation show tumour necrosis factor receptor associated factor 1 (TRAF1) expression (red staining) in numerous Epstein-Barr virus (EBV) positive (black grains over nuclei of infected cells) cells in infectious mononucleosis, whereas (B) isolated EBV positive cells in chronic virus carriers are TRAF1 negative. (C, D) Immunohistology reveals TRAF1 expression (red labelling) in Hodgkin and Reed-Sternberg cells in cases of Hodgkin lymphoma. (E) In follicular lymphomas, scattered cells at the margin of the neoplastic follicles express TRAF1. (F) Anaplastic large cell lymphomas show weak expression of TRAF1 in a proportion of tumour cells. Note that C, D, E, and F illustrate immunohistochemical staining without simultaneous EBV specific in situ hybridisation.