EVALUATION OF RECOMBINANT RO SSA, LA/SSB, SM, AND U1 RNP AUTOANTIGENSIN CLINICAL-DIAGNOSIS/

This study comprises an analysis of the diagnostic usefulness of Ro/SS A, La/SSB, Sm and UI RNP autoantigens obtained by DNA recombinant tech nology. We studied the presence of these autoantibodies in 33 patients with systemic lupus erythematosus (SLE) and 30 normal individuals by enzyme-linked immunosorbent assay (ELISA) using recombinant autoantige ns and by Western immunoblot with these same antigens obtained from na tural sources (rabbit thymus and human spleen). The strength of agreem ent between results found with these two techniques was moderate in th e case of anti-Ro/SSA (kappa=0.474, P<0.001) and anti-U1 RNP (kappa=0. 566. P<0.001) antibodies and almost perfect in the case of anti-La/SSB (kappa=0871, P<0.001) and anti-Sm (kappa=0.833, P<0.001). Furthermore , analysis of the disagreement between the two techniques evidenced a measurement bias for anti-Ro/SSA and anti-U1 RNP antibodies (Mo NEMAR' S statistic 13 and 11, respectively) whose direction, though difficult to define in the absence of a gold standard for such determinations, could be accounted for by the ELISA technique's greater tendency to pr oduce positive results. Our conclusion is that the diagnostic usefulne ss of recombinant La/SSB and Sm autoantigens has been satisfactorily p roven, whereas the case of the Ro/SSA and U1 RNP systems should be sub ject to further in-depth study of the autoepitopes recognised and the possible modifications which the latter might undergo as a result of t heir obtension from procariotic sources. (C) 1995 Wlley-Liss, Inc.