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 C3 degradation products. - Lim,K.L.; Jones,A.C.; Brown,N.S.; Powell,R.J. (Ann Rheum Dis, 1993)