[The expression and significance of major histocompatibility complex II transactivator gene in five human malignant...

To investigate the role of major histocompatibility complex (MHC) II transactivator in constitutive or interferon (IFN)-gamma inducible expression of MHC molecules in human malignant hematological cell lines.

The expression of MHC molecules and MHC class II transactivator (CIITA) protein were detected with Western blot, immunohistochemistry and flow cytometry. The expression of CIITA gene was determined with RT-PCR. T cell expressing interleukin (IL)-2 mRNA was induced by Jurkat with mixed lymphocyte reaction.

It was found that the MHCII-positive tumor cells expressed the CIITA quite well, and IFN-gamma could induce the expression of MHCI + II only if the tumor cells were able to express CIITA in an IFN-gamma induced manner (20%, 42% for Jurkat cells respectively), while T cell expressed more IL-2 mRNA (51 times) in the case of Jurkat after induction with IFN-gamma.

It is suggested that there is a correlation between the inability of the tumor cells in response to IFN-gamma for MHC expression and the deficiency in the inducible expression of CIITA. This might be due to immune sneaking through the tumor cells to some extent.