VH4-34 encoded antibodies in systemic lupus erythematosus: A specific diagnostic marker that correlates with clinical disease characteristics

Objective, To determine the clinical significance of elevated serum levels of VH4-34 encoded antibodies (VH4-34 Ab) with respect to the diagnosis and clinical characteristics of systemic lupus erythematosus (SLE), Methods, Ninety-five patients with SLE and 344 controls were studied. The c ontrols included 34 healthy individuals, 282 patients with nonautoimmune di seases, and 28 patients with autoimmune diseases other than SLE. VH4-34 Ab levels were measured by inhibition ELISA using anti-idiotope monoclonal ant ibody (9G4). SLE disease activity, severity, and damage were assessed by vi sual analog scales, Systemic Lupus Activity Measure, Lupus Severity of Dise ase Index, and Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index. Results. Fifty-two of 95 patients with SLE had elevated levels of VH4-34 Ab compared to 18 of 344 controls (5%), giving a sensitivity of 55% and a spe cificity of 95% for elevated VH4-34, Ab as a serologic test for SLE. The po sitive predictive value of elevated VH4-34 under these conditions was 74-85 %. In this study, anti-dsDNA was not VH4-34 encoded. Significant correlatio ns between VH4-34 and disease activity and severity indices were observed ( r = 0.29-0.50). The relative risk for severe disease in SLE patients with V H4-34 antibody level in the highest tertile compared to the lowest tertile was 5.25. Twenty-five of 29 patients with lupus nephritis and 6 of 6 patien ts with central nervous system (CNS) lupus had elevated VH4-34 Ab. Conclusion. With a specificity of 94-95%, the VH4-34 antibody assay may pro ve valuable as a confirmatory diagnostic test for SLE. In patients with kno wn SLE, serum VH4-34 Ab levels correlate with overall disease severity and activity, but not damage, and with nephritis and CNS lupus.