Diagnostic value of serum interferon level in systemic lupus erythematosus.

In all the patients with systemic lupus erythematosus (SLE) tested in the active phase of the disease the serum interferon (IFN) level increases above the normal value (20 I.U./ml) reaching in some cases 80-160 I.U./ml. The detection of this increased level of IFN is useful to discriminate if some diseases such as glomerulonephritis or hemolytic anemias develop as part of a systemic auto-immune disorder since in such pathologic conditions lacking auto-immune mechanisms the serum IFN level is not increased. The detection of the serum IFN level proved to be a useful test in the follow-up of the clinical evolution as well as for the efficiency of the immunosuppressive therapy since in all the investigated cases IFN level decreased to normal after Cortisone administration concomitantly with the clinical remission of the disease. The above described data support the assumption that in the pathogeny of auto-immune diseases, SLE in our case, there are some initial cell-mediated auto-immune phenomena such as cell-mediated auto-cytotoxicity leading to a massive activation of the CTL and NK cells and consequently to the over-production of some lymphokines such as IFN.