A previous study found an upgrade and clustering of OX40 on CD4+ T-cells in SLE, indicating its activation.14 Another study on experimental rabbits reported an improvement in SLE and a decline in the SLEDAI score upon administration of monoclonal antibodies against OX40.15 On the other hand, an earlier smaller study had reported that the difference between SLE patients and control subjects did not reach statistical significance.16 However, this could be attributed to the small number (8) of patients used in that study. This evidence concerns the gene CD4 and systemic lupus erythematosus.