Anti-SM (B/B/D) antibodies

These antibodies belong to the ANA. The Sm antigen (non-histoneSmith (Sm) antigen) is present in the cell nucleus and belongs to the group of small ribonucleoproteins (snRNP, smallnuclearribonucleoproteins. Irrespective of the individual ribonucleic acid component, each particle of nuclear RNA can contain six different nuclear proteins (B, B', D, E, F, G). Antibodies are directed exclusively to epitopes located on the proteins. Antibodies to the Sm component are detected in about 20-30% of patients with systemic lupus erythematosus. Negative results for the anti-Sm antigen do not rule out the presence of this autoimmune disease. The absolute specificity of anti-Sm antibodies in systemic lupus erythematosus should be noted, which has led to their inclusion in the 10th criterion for SLE (along with antibodies to dsDNA and LE-cells). The concentration of anti-Sm antigen does not change with therapy for systemic lupus erythematosus, however, so their monitoring is of no clinical relevance. Only rarely are antibodies to the Sm component detected in isolation and are usually detected in combination with antibodies to the Sm/RNP complex. The clinical features associated with the presence of Sm antibodies are a more aggressive course of the disease, CNS damage, lupus psychosis and the relative survival of renal function.