BTLA and lupus nephritis: There was no significant difference in the expression of BTLA on stimulated Th1-cells in healthy controls as compared to SLE patients with lupus nephritis (29.3% ± 11.0% vs. 43.2% ± 31.0%, p = 0.23) nor compared to SLE patients without lupus nephritis (29.3% ± 11.0% vs. 35.0% ± 14.8%, p = 0.37).