Hodgkin's lymphoma caused for by

Ref Robbins 9/e p607 One clue stems from the involvement of EBV. EBV is present in the RS cells in as many as 70% of cases of the mixed-cellularity subtype and a smaller fraction of other "classical" forms of Hodgkin lymphoma. More impoant, the integration of the EBV genome is identi- cal in all RS cells in a given case, indicating that infection precedes (and therefore may be related to) transformation and clonal expansion. Thus, as in Burkitt lymphoma and B cell lymphomas in immunodeficient patients, EBV infection prob- ably is one of several steps contributing to tumor develop- ment, paicularly of the mixed-cellularity subtype. The characteristic non-neoplastic, inflammatory cell infil- trate is generated by a number of cytokines, some secreted by RS cells, including IL-5 (which attracts and activates eosin- ophils), transforming growth factor-b (a fibrogenic factor), and IL-13 (which may stimulate RS cells through an autocrine mechanism). Conversely, the responding inflammatory cells, rather than being innocent bystanders, produce additional factors such as CD30 ligand that aid the growth and survival of RS cells and contribute fuher to the tissue reaction.