Immune function parameters of the mutated IFN-γR1. (a) TNF-α production by monocytes stimulated with medium, LPS, and LPS plus rhIFN-γ; (b) induction of CD64 in monocytes after stimulation with IFN-γ. ▵, isotypic control fluorescence; ○, expression of CD64 after 24 h of stimulation with medium alone; □, expression of CD64 after 24 h of stimulation with 1,000 IU of rhIFN-γ/ml.