URINE NEOPTERIN AS A PARAMETER OF DISEASE-ACTIVITY IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS - COMPARISONS WITH SERUM SIL-2R AND ANTIBODIES TO DSDNA, ERYTHROCYTE SEDIMENTATION-RATE, AND PLASMA-C3, C4, AND PLASMA-C3 DEGRADATION PRODUCTS

Objectives-To investigate urine neopterin as a parameter of disease ac tivity in an unselected group of patients with systemic lupus erythema tosus (SLE) and to study the relation between urine neopterin and cert ain patterns of organ disease and differing drug regimens in the treat ment of SLE. Methods-Neopterin was determined by high performance liqu id chromatography in 115 early morning urine samples from 68 patients with SLE. Serum soluble interleukin 2 receptor (sIL-2R) and antibodies to double stranded DNA (dsDNA) were determined by enzyme linked immun osorbent assay (ELISA), and the erythrocyte sedimentation rate (ESR), plasma C3, C4, and C3 degradation products (C3dg) were measured in cor responding blood samples. Disease activity was scored using the Britis h Isles Lupus Assessment Group (BILAG) index. Results-Urine neopterin was significantly increased in patients with active and inactive SLE c ompared with the control group and was significantly higher in patient s with active than in those with inactive SLE. Urine neopterin did not distinguish between subsets of patients with SLE with particular patt erns of organ disease, as defined by the BILAG index, nor was its leve l primarily influenced by differing drug regimens. Levels of serum sIL -2R, antibodies to dsDNA, the ESR, and plasma C3, C4, and C3dg were al so significantly different between the patients with active and inacti ve SLE. Unlike urine neopterin there was considerable overlap in the v alues of these parameters between the two activity groups. Highly sign ificant correlations found between urine neopterin and serum sIL-2R, E SR, and plasma C3, C4, and C3dg suggest the close association of neopt erin with clinical activity in SLE. Multivariate logistic regression a nalysis showed that urine neopterin >300 mumol/mol creatinine was a hi ghly significant predictor of disease activity with an odds ratio of 3 .51. Conclusions-Determination of urine neopterin, a non-invasive, rel atively simple and inexpensive measurement, appears to be the best par ameter for assessing and monitoring disease activity and treatment in patients with SLE.