They also observed a positive correlation between disease activity, percentage of blood TFH cells and frequency of OX40L+myeloid APC, suggesting OX40L-OX40 axis as a contributor factor in the aberrant TFH response observed in SLE.46 47 However, the ability to study tissue TFH in humans is limited. Here, TNFSF4 is linked to systemic lupus erythematosus.