Abstract: Background and purpose: Sentinel lymph node biopsy is regarded as the standard of care in patients without clinical axillary lymph node metastases in early-stage breast cancer. Accurate detection of sentinel lymph node is an important step for staging, prognosis, and treatment. In this study, a new sentinel lymph node tracer was produced by the rituximab to combine with the fluorescence tracer (indocyanine green, ICG), and to identify the most appropriate combination ratio of the two agents. Its biological property and safety limitation were evaluated. Methods: Rituximab was combined directly with ICG. The new tracer was analyzed for labeled rate by instant thin-layer chroma-tography-silica gel, molecular integrity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and molecular immune activity by ELLAS. The safety limitation was tested according to the Chinese Pharmacopeia. The localization ability of sentinel lymph node was tested in mice. Results: The new tracer was intact and kept the immune activity of rituximab. The ICG labeled rate of rituximab was 100%. The new tracer was bacteria and pyogen free, and was safe to body with location injection. The most appropriate combination ratio of rituximab and ICG was 4∶1 and 6∶1 with the best sentinel lymph node imaging. The location of sentinel lymph node identified by the new tracer was accorded with the radiotracer. Conclusion: The preparation method of the new sentinel lymph node tracer is simple and no radioactive injury. The new tracer has no bacteria, no pyogen and no acute toxicity, and can be used in sentinel lymph node visualization.

Key words: Sentinel lymph node, Imaging agent, Rituximab, Indocyanine green, Lymphoscintigraphy