We detected significant differences in the expression of BTLA in stimulated Th1-cells between healthy controls and active SLE patients (CD3+CD8−CD69+ IFN-γ+: %BTLA, 29.3% ± 11.0% vs. 59.7% ± 27.7%, p = 0.023) and in comparison of active versus inactive SLE patients (59.7% ± 27.7% vs. 33.0% ± 25.0%, p = 0.049, Figure 3D). The gene discussed is IFNG; the disease is systemic lupus erythematosus.