<prompt> Siltuximab is used in treatment of ?Castlemans diseaseSezary syndromeAnkylosing spondylitisNon hodgkins lymphoma  <response>: Ans. is a i.e., Castlemans diseaselRef: Multiple myeloma, an issue of hematology oncology clinics E boohKenneth C Anderson p. 9171Siltuximab Anti IL-6:IL-6 is produced by the stromal cells of the bone marrow, and plays a crucial role in the proliferation and survival of multiple myeloma cells. 