CD28 and systemic lupus erythematosus: Diminished GRAIL expression seen in the Tregs from SLE patients (Figure 3) was accompanied by a loss of inhibition of IL-2R desensitization (Figure 2) and defective regulatory function when CD4+CD25- effector and CD4+CD25+ regulatory T cells from the SLE patients in Figure 3 were studied in autologous co-cultures (effector:regulatory T cells ratio 1:1) in 24-well plates and were either left unstimulated (RPMI), or were activated by means of the combination of plate-bound anti-CD3 antibody (5 μg/ml) and soluble anti-CD28 antibody (2.5 μg/ml) for 48 hours.