RO(SS-A) AND ANTI-RO(SS-A) - AN UPDATE

Anti-Ro/SSA antibodies are the antinuclear antibodies most commonly fo und in everyday clinical practice and are closely associated with Sjog ren's syndrome, systemic lupus erythematosus and neonatal lupus. They play a pathogenic role in a variety of clinical manifestations, includ ing skin lesions and neonatal lupus heart block. Autoantibodies to Ro( SS-A) recognize a ribonucleoprotein complex composed of small single-s tranded RNAs (hYRNAs) and of one or more peptides. Four molecular form s of this complex have been differentiated based on the nature of the peptide: a lymphocyte and an erythrocyte Ro with a 60 kDa peptide, a l ymphocyte Ro with a 52 kDa peptide and an erythrocyte Ro with a 54 kDa peptide. The Ro complex is found in most tissues and cells (erythrocy tes, platelets), with differences in structure and quantity across tis sues, species and embryonic development stages. Although its function remains unknown, its ability to bind nucleic acids and the fact that i t shares homologies with gene regulation proteins suggest that it may participate in RNA transcription processes. A number of environmental factors (exposure to ultraviolet radiation, viral infections) may caus e translocation of the Ro complex to nucleocytoplasmic and membrane si tes where it is not normally found, thereby leading to the development of autoimmunity. The structure of the Ro(SS-A)-hYRNA complex and the development of autoimmunity are currently the focus of active research efforts that can be expected to improve our understanding of the clin ical manifestations directly related to anti-Ro(SS-A) antibodies.