Background: Interleukin-6 is dysregulated in multiple pathological conditions, e.g. cancer and inflammatory diseases. Aim: To investigate new mechanisms for regulation of pathological IL-6 production. Methods: PBMC produce interleukin-6 (IL-6) stimulated by cancer serum factors or specific peptides. Immunoregulatory albumin neo-structures and peptides were identified with 2D-gel electrophoresis and MALDI-TOF-MS analyses. Il-6 and albumin neo-structures were determined by ELISA. Results: Conformational changes of normal serum albumin by proteolytic degradation generates an IL-6 inducing neo-structure, IL-6 inducing factor (IL-6IF), which is immunogenic eliciting production of autoantibodies. IL-6 production induced by IL-6IF and cancer patient sera is inhibited by specific antibodies. The serum concentration of IL-6IF, is significantly higher in advanced cancer stages and its presence is significantly correlated to the survival of the patients. Conclusion: A new mechanism for induction IL-6 synthesis is presented. Based on this mechanism the pathological IL-6 production related to an enhanced proteolytic activity can be diagnosed and selectively inhibited by specific antibodies. Such antibodies have been identified and purified. Thus, the neo-structure, inducing pathological IL-6 production, associated with a reduced survival of cancer patients can be selectively removed by therapeutic administration of antibodies leaving the function of IL-6 needed for the normal activity of the immune system intact.