TRIM21 and systemic lupus erythematosus: In order to characterize the SLE cohort with regard to autoantibody profiles, 101 SLE patient sera were tested for U1-68 kD, U1-A, U1-C, SmBB', SmD, Ro-52/SS-A, Ro-60/SS-A, La/SS-B, histone, dsDNA and β2-glycoprotein I reactivity.