Negative double stranded DNA and anti-Smith antibodies in lupus nephritis

Systemic lupus erythematosus (SLE) is an autoimmune disease in which auto-antibodies are generated against a variety of intracellular antigens. Anti-Smith (Sm) and anti-double stranded DNA (dsDNA) antibodies in particular are considered to be nephritogenic and their role and correlation with lupus nephritis (LN) has been well established. We present here a case in which the patient had diffuse proliferative full house severe LN, yet negative ds-DNA and anti-Sm antibodies. Although extremely rare, a few subsets of patients with drug-induced LN (hydralazine) have been described in the literature to have negative dsDNA and anti-Sm antibodies on serological screening. Our patient, however, had no evidence of drug induced LN. On further review, and similar to our case, we found only 6 additional well documented cases of non-drug induced severe LN with negative dsDNA antibodies.