Anti-U1-ribonucleoprotein antibodies U1RNP

General Information

Anti-U1 ribonucleoprotein antibodies (anti-U1-RNP) are autoantibodies to the nuclear antigen characteristic of connective tissue diseases.

Anti-U1 ribonucleoprotein antibodies interact with the antigen - small nuclear riboprotein particles, they differ from SM (Smith) antibodies.

Both types of antibodies are determined through a single test system. Unlike Smith antibodies, anti-U1-RNP antibodies are not found in systemic lupus erythematosus. It is more typical in mixed connective tissue disease, rheumatoid arthritis, Sjögren's syndrome, systemic sclerosis, and inflammatory myositis.

In mixed connective tissue disease, anti-U1-RNP antibody titers are positive, and Smith (SM) and double-stranded-DNA (DS-DNA) antibodies are negative.