BACKGROUND: 1E10 monoclonal antibody is a murine anti-idiotypic antibody that mimics N-glycolyl-GM3 gangliosides. This antibody has been tested as an anti-idiotypic cancer vaccine, adjuvated in Al(OH)3, in several clinical trials for melanoma, breast,andlung cancer. During early clinical development this mAb was obtained in vivo from mice ascites fluid. Currently, the production process of 1E10 is being transferred from the in vivo to a bioreactor-based method. RESULTS: Here, we present a comprehensive molecularandimmunologicalcharacterizationof 1E10 produced by the two different production processes in order to determine the impact of the manufacturing process in vaccine performance. We observed differences in glycosylation pattern, charge heterogeneityandstructural stability between in vivo-produced 1E10andbioreactor-obtained 1E10. Interestingly, these modifications had no significant impact on the immune responses elicited in two different animal models. CONCLUSIONS: Changes in 1E10 primary structure like glycosylation; asparagine deamidationandoxidation affected 1E10 structural stability but did not affect the immune response elicited in miceandchickens when compared to 1E10 produced in mice.