U1-RNP-Ab ELISA

Enzyme immunoassay qualitatively and quantitatively determine IgG antibodies against U1-RNP in human serum. The uracil-rich small nuclear RNA (U-snRNA) and protein are physiologically compounded into ribonucleoprotein particles (U-snRNP), and ribonucleoprotein particles are involved in the splicing process of pre-mRNA. Different complexes (U1-U6) can be distinguished according to the RNA involved. Their protein components are partly the same and partly different. For example, U1-snRNA is complexed with the so-called Sm protein and U1-specific proteins A, C and 68 kDa that are also present in other U-snRNPs. Autoantibodies against these three U1-specific proteins are regarded as diagnostic markers for mixed connective tissue disease (MCTD). They are also associated with systemic lupus erythematosus (SLE), but the incidence is significantly lower (about 35%), and they are mostly used in combination with other antinuclear antibodies (ANA).