Derived from a CTCL patient's HH cell line, this stable cell line, HH/JAK-Stat Pathway Firefly luciferase Reporter, is widely used in immunology and cancer research, especially for studying T-cell signaling, cytokine responses, and skin-associated lymphoid malignancies. It exhibits a CD4+ T-cell phenotype, produces IL-2 receptor (CD25), and responds to IL-2 stimulation. It has served as a model for Sezary syndrome and mycosis fungoides, growing in suspension with careful cell density monitoring required.