Symphony (ENA screen, extractable nuclear antigens)

Extractable antinuclear antibodies (ENA screen) are a group of autoantibodies to the components of the cell nucleus. The reason for their appearance is a malfunction of the immune system, which begins to show aggression to the structures of its own body. The word “extractable” means that the proteins necessary for the analysis are “extracted” from the cell nucleus.

The test is prescribed for patients who have clinical signs of autoimmune diseases. The symptoms of such diseases are quite varied.

They may include:

• Fever and constant fatigue;
  
• Muscle aches;
  
• Joint swelling and/or pain;
  
• Skin rashes;
  
• Sensitivity to ultraviolet light;
  
• Raynaud's phenomenon (numbness and pale fingertips);
  
• Kidney damage (proteinuria, hematuria);
  
• Neurologic symptomatology;
  
• Hemolytic anemia or low white blood cell count (leukopenia).
  

The main representatives of the extractable antibody group are: SS-A/Ro, SS-B/La, Sm, RNP/Sm, Scl-70, Jo-1.

SS-A/Ro. Most often the detection of such antibodies in the blood indicates Sjögren's syndrome, less often they are found in SLE. In addition, detection of these antibodies in pregnant women can be interpreted as the presence of atrioventricular heart block in the fetus.

SS-B/La is usually found in combination with SS-A/Ro antibodies and increases the likelihood that the patient has Sjögren's syndrome.

Sm is found only in SLE patients, never, even in low titers, found in normal blood.

RNP/Sm are less specific antibodies, because along with SLE, may also indicate the presence of rheumatoid arthritis or scleroderma.

Scl-70 is the most specific antibody when a patient develops scleroderma, in normal conditions, as well as Sm antibodies, is never found.

Jo-1 are characteristic antibodies in patients with polymyositis and dermatomyositis.

Appearance in the blood of extractable antinuclear antibodies, even in the lowest titers, almost with a hundred percent probability indicate the presence of autoimmune disease of connective tissue in the patient, and already from what of the antinuclear antibodies predominate in the blood, you can judge what kind of disease developed in the patient. Only in isolated cases, antibodies may be present in healthy individuals without any clinical manifestations.

In addition, extractable antinuclear antibodies can indicate the degree of progression of an autoimmune disease by prescribing repeated tests at regular intervals to determine whether the antibody titer in the blood is increasing or decreasing.