CD4 and atopic eczema: In inflammatory disorders, TIGIT expression is differentially regulated, e.g., TIGIT is upregulated upon TCR triggering or on EM CD4+ T cells and Tregs in mild atopic dermatitis, while downregulated on CD4+ T lymphocytes in psoriasis patients and severe atopic dermatitis, both negatively correlated with disease severity (Table 2) [26,27,29].