Methods for diagnosing systemic lupus erythematosus

Abstract

The present invention provides methods of diagnosing and monitoring systemic lupus erythematosus.

What is claimed is: 
     
         1 . A method for treating systemic lupus erythematosus in a human subject in need thereof, the method comprising:
 (a) measuring a level of erythrocyte-bound C4d (EC4d) marker, B-lymphocyte-bound C4d (BC4d) marker, and anti-nuclear antibody (ANA) in a blood sample obtained from the human subject;   (b) administering to the human subject an effective amount of cyclophosphamide, a corticosteroid, mycophenolate, methotrexate, azathioprine, leflunomide, belimumab, or hydroxychloroquine to treat systemic lupus erythematosus;   
       wherein the human subject is negative for systemic lupus erythematosus based on their level of double-stranded DNA. 
     
     
         2 . The method of  claim 1 , wherein the level of EC4d marker in the blood sample is measured with fluorescence-activated cell sorting. 
     
     
         3 . The method of  claim 1 , wherein the level of BC4d marker in the blood sample is measured with fluorescence-activated cell sorting. 
     
     
         4 . The method of  claim 1 , wherein the level of ANA in the blood sample is measured an enzyme-linked immunosorbent assay or fluorescence-activated cell sorting. 
     
     
         5 . The method of  claim 1 , wherein measuring the level of EC4d marker comprises measuring the level of EC4d on the surface of erythrocytes. 
     
     
         6 . The method of  claim 1 , wherein measuring the level of BC4d marker comprises measuring the level of BC4d on the surface of B lymphocytes. 
     
     
         7 . The method of  claim 1 , further comprising applying a transformation analysis to the level of EC4d marker, BC4d marker, and ANA. 
     
     
         8 . The method of  claim 1 , wherein the human subject has a level of EC4D marker that is less than 6 standard deviations above the mean EC4D marker among non-lupus patients. 
     
     
         9 . The method of  claim 1 , wherein the human subject has a level of BC4D marker that is less than 6 standard deviations above the mean BC4D marker among non-lupus patients.