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K-562 cells lack MHC class II expression due to an alternatively spliced CIITA transcript with a truncated coding
Noel E Day1, Hideyo Ugai, Kazunari K Yokoyama
1Department of Medical Genetics, Graduate School of Medicine, The University of Tennessee Medical Center, 1924 Alcoa Highway, Knoxville, TN 37920, USA.
Abstract:
The focus of this study was to determine the functional capacity of class II transactivator (CIITA), a regulatory factor of major histocompatibility complex (MHC) class II genes, in K-562 cells. We show that CIITA mRNA is present in K-562 cells and the interferon-gamma (IFN-gamma)-inducible CIITA promoter-IV exhibits low levels of basal activity, which is greatly enhanced upon treatment with IFN-gamma. Further study revealed that the CIITA cDNA contains an insertion of genomic sequence, which introduces a stop codon. The truncated coding region of the CIITA transcript in K-562 cells provides a possible explanation for the absence of MHC class II molecules.