Here we report the cloning of the rat 90K, a homolog of the mouse cyclophilin C-associated protein/mouse adherent macrophage and human 90K. The protein is constitutively expressed by FRTL-5 thyrocytes, and its levels are modulated by TSH, insulin/IGF-I, and gamma-interferon. Transfection of the cells with 90K cDNA or exposure to purified 90K resulted in a significant increase of the expression of major histocompatibility complex class I but not class II antigens. An increased expression of 90K was obtained after viral infection or introduction into the cells of fragments of viral, bacterial, or mammalian double-strand polynucleotides. The increase was sequence independent, not CpG mediated, and associated with the expression of molecules characterizing antigen-presenting-cell phenotype. The present data along with results from previous studies suggest that 90K plays an important role in the maintenance of an appropriate level of immune response.

No abstract

These results suggest that fibrin gel could be useful as a delivery system for hMSCs.