The persistent challenge of lupus nephritis.

Systemic lupus erythematosus has long been considered the prototypic autoimmune disease. Although the etiology remains enigmatic, there has been vigorous definition of the clinical features and the natural history. In this issue, we review the persistent challenge of lupus nephritis and, in particular, features of diagnosis as well as treatment options. It is clear that major therapeutic advances have occurred but there is still a considerable unmet need in the population. This issue does not review all the clinical problems of lupus nephritis, but rather attempts to place the most recent data in perspective for the clinician.