Human RNP/Sm Ab ELISA kit can be used for detecting in-vitro quantitative amounts of IgG autoantibodies to ribonucleoprotein and Anti-Smith (RNP/Sm antibody, anti-RNP/Sm, RNP/Sm Ab) in human plasma and serum. This assay has a minimum analytical sensitivity limit of 1.0 U/ml.


A selection of antinuclear antibodies such as ribonucleoprotein antibodies (RNP), anti-smith (anti-Sm) and anti-double-stranded deoxyribonucleic acid (dsDNA) are known to be highly specific in aiding the diagnosis of systemic lupus erythematosus (SLE). In the case of antibodies against U1 ribonucleoprotein (RNP) complex, these are vital markers for mixed connective tissue disease (MCTD), can also be found in patients having SLE and numerous other diseases such as scleroderma, polymyositis and Sjögren’s syndrome. Elevated levels of antibodies to RNP can be found in MCTD patients whereas in SLE patients RNP antibodies have been linked to relatively benign disease that have lower incidence of central nervous system and renal involvement. Patients are generally considered positive for RNP antibodies RNP antibody result is significantly greater than that of the Sm antibody result.


All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

  • Divisible Microplate: Consisting of 12 modules of 8 wells, highly purified RNP/Sm antibodies bound to microwells.
  • Calibrators (A-F): Concentrations 0, 12.5, 25, 50, 100, 200 U/ml, made up from anti-RNP/Sm in a serum/buffer matrix.
  • Controls Positive and Control Negative: Containing human anti-RNP/Sm antibodies.
  • Sample Buffer P.
  • Enzyme Conjugate: Contains anti-human IgG antibodies, HRP labelled.
  • TMB Substrate.
  • Stop Solution: Contains acid.
  • Wash Buffer (50x Concentrated).
  • Instruction Manual.
  • Certificate of Analysis.


The minimum detection sensitivity level of human ribonucleoprotein and Anti-Smith IgG auto-antibodies (RNP/Sm Ab, anti-RNP/Sm, RNP/Sm antibody) using current anti-RNP/Sm ELISA kit was 1.0 U/ml. The dynamic range for this assay is 12.5 – 200.0 U/ml.


– Ribonucleoprotein/Anti-Smith Antibody (Anti-RNP/Sm): ELISA
– Measuring Range: 0 – 200 U/ml
– Limit Of Detection (LOD): 1 U/ml.
– Results Interpretation: Negative: < 25 U/ml, Borderline 15-25 U/ml, Positive: ≥ 25 U/ml.
– Expected Values: Cut-off 25 U/ml.
– Linearity: 97 – 100%
– Intra Assay Precision: 1.8 – 5.9%
– Inter Assay Precision: 2.9 – 4.2%
– Interference: None.
– Clinical Diagnosis: Sensitivity (66.0%), Specificity (95.8%), Overall agreement (82.3%).


  1. An immunoassay differentiating sera with antibodies to Sm alone, antibodies to Sm/RNP complex, and antibodies to RNP alone. Arthritis Rheum. (1987) 30 (4): 389-96. Tsay G.J., et al.
  2. The relationship between Sm and RNP antigens. Clin Immunol Immunopathol. (1986) 41 (1): 91-107. Fronek Z., et al.
  3. Anti-Sm and anti-RNP antibodies. Autoimmunity. (2005) 38 (1): 47-54. Review. Migliorini P., et al.
  4. Two major autoantibody clusters in systemic lupus erythematosus. PLoS One. (2012) 7 (2): e32001. Ching K.H., et al.
  5. Contrasting molecular patterns of MHC class II alleles associated with the anti-Sm and anti-RNP precipitin autoantibodies in systemic lupus erythematosus. Arthritis Rheum. (1993) 36 (1): 94-104. Olsen M.L., et al.
  6. Antibodies to Sm and RNP. Prognosticators of disease involvement. Arthritis Rheum. (1983) 26 (7): 848-53. Munves E.F. and Schur P.H.


  • Full Name: RNP/Sm Ab ELISA Kit
  • Reactivity: Human
  • Sample Type: Plasma, Serum
  • Sensitivity: 1.0 U/ml



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