CD81 and Pleural effusion: Exosomes isolated from pleural effusion from MPM patients have lower levels of CD9, CD63, CD81, CD2, CD8, CD14, CD29, CD44, CD49e, CD62p, CD105, CD146, CD326, HLA-ABC, and MCSP and higher levels of HLA-DRDPDQ and ROR1 surface proteins compared to AD patients.