Human chromosome 21 is necessary and sufficient to confer human IFN gamma responsiveness to somatic cell hybrids expressing the cloned human IFN gamma receptor gene.

The human interferon (IFN) gamma receptor cDNA has been stably expressed in human/mouse somatic cell hybrids, which differ in their content of human chromosome 21. Despite high affinity IFN gamma binding-capacity of all receptor transfectants, biological responsiveness to IFN gamma, as determined by enhancement of mouse-MHC class I gene expression, required the presence of chromosome 21. These data suggest complementation of at least two functionally distinct components in order to create a biologically active IFN gamma receptor.