Protocol for isolation of interstitial fluid from tumor-draining lymph nodes for proteomic profiling in murine breast cancer models.

Tumors release soluble factors that reach tumor-draining lymph nodes (TDLNs), where they induce remodeling already at the pre-metastatic stage and alter the local proteomic landscape. Here, we describe a protocol for isolating interstitial fluid from primary tumors and TDLNs in murine breast cancer models to study extracellular protein composition while preserving tissue viability and integrity. We outline key steps for tissue preparation, fluid extraction, and downstream bioinformatic analysis to support the characterization of tumor-associated changes in TDLNs. For complete details on the use and execution of this protocol, please refer to Mattavelli et al.1.