CD81 and Sepsis: Within the immune system, CD81 is instrumental in regulating immune synapses, the clustering of receptors, and the process of signal transduction.[37] Additionally, as a member of the tetraspanin integral membrane protein family, CD81 has been identified as an essential receptor for HCV (hepatitis C virus).[38] Our survival curve analysis revealed that increased expression of CD81 in groups with a better prognosis of sepsis led to higher survival rates.