CD35

CD35, also known as complement receptor 1 (CR1), is a polymorphic single-chain membrane-bound protein that exists in follicular dendritic cells (FDCs). It can fix immune complexes and provide antigenic reservoir for lymphocytes to participate in the development and activation of the immune system. In clinical practice, CD35 has become an essential diagnostic biomarker for follicular dendritic cell sarcoma (FDCS), and it is not expressed in interdigitating dendritic cell sarcoma, myofibroblastoma, and metastatic spindle cell carcinoma, which makes it useful for assisting in identification. Meanwhile, CD35 mainly exists in red blood cells, which can adhere to immune complexes and transport them to liver and spleen macrophages, preventing the occurrence of autoimmune diseases. In patients with malignant tumors such as lung cancer, gastric cancer, and colorectal cancer, CD35 decreases in red blood cells but increases in platelets, which will weaken the natural immune function of red blood cells and activate platelet capture to initiate hematogenous metastasis of cancer cells. Therefore, the CD35 expression change can provide clues for predicting tumor progression.