Systemic rheumatic diseases are autoimmune disorders with symptoms of systemic inflammation. The immune system attacks vital organs including the lungs, heart, nervous system, kidneys, skin and eyes; however, muscle-joint symptoms are the most common manifestations of the disease. In the differential diagnosis of individual systemic autoimmune diseases, the determination of ANA - antinuclear antibodies and their typing is important. In particular, these diseases are: systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), scleroderma, then mixed connective tissue disease (MCTD), systemic sclerosis, polymyositis and dermatomyositis. An important separate group of antinuclear antibodies are ENA - antibodies against extractable nuclear antigens (SS-A/Ro, SS-B/La, Sm, RNP, Scl-70, and Jo-1). Antinuclear antibodies also include antibodies to nucleic acids (ssDNA, dsDNA), nuclear protein complexes (DNP, RNP) and histones.
Rheumatoid arthritis (RA) is a systemic disease manifesting as a chronic inflammatory disease with involvement of all joints with the most pronounced manifestations on the limbs, resulting in destructive polyarthritis. The most used laboratory test in the diagnosis of the disease is the determination of rheumatoid factor (RF). RF determinations of individual classes IgA, IgG and IgM and anti-CCP antibodies correlate with disease activity and disease prognosis.