1.Anti-nuclear antibody (ANA)
Anti-nuclear antibody is a general term for a group of anti-serum auto-antibodies against many nuclear components of cells.ANA can be seen in many rheumatic diseases, including systemic lupus erythematosus (SLE), drug-related lupus, mixed connective tissue disease (MCTD), rheumatoid arthritis (RA), dry syndrome (SS), systemic sclerosis (PSS), polymyositis (PM)/dermatomyositis (DM) and Chronic active hepatitis, etc.
2.Anti-double-stranded DNA antibody (anti-ds-DNA antibody)
There are two types of DNA: double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA). Autoantibodies against the former are marker antibodies for systemic lupus erythematosus, while the latter are seen in a variety of rheumatic diseases.
3.Rheumatoid factor (RF)
Rheumatoid factor is an autoantibody that targets the Fc segment of degenerated IgG and is present in the serum and joint fluid of patients with rheumatoid arthritis and certain autoimmune diseases. RF can be divided into four types: IgM, IgG, IgA and IgE. The clinical significance of RF is that it is important for the diagnosis of rheumatoid arthritis, with a positive rate of 60-80%. patients with persistent positive IgM-RF are more likely to develop bone erosion. IgM-RF titers correlate with signs of RA disease activity, such as the number of joint pain and joint swelling, and are a reliable and sensitive indicator of RA disease activity.
4.Cyclic guanosine polypeptide antibody (CCP antibody)
Anti-CCP antibodies are autoantibodies against cyclic guanosine polypeptide fragments, mainly of IgG type. Anti-CCP antibody is a highly specific antibody for rheumatoid arthritis, with a positivity rate of 51% and specificity >96%, and has a strong correlation with the prognosis of rheumatoid arthritis.
5, anti-RA-33 antibody (anti-RA33 antibody)
Anti-RA-33 antibody is a specific antibody against the nucleoprotein of Hela cells. Its target antigen is a 33kD nucleoprotein. Among the early diagnostic indicators of RA, anti-RA33 antibody has a high specificity, with a positive rate of 35.85%. The length of the antibody is not related to the disease and medication.
6.Anti-keratin antibody (AKA)
The detection of AKA antibodies provides a diagnostic indicator for RA patients who are negative for RF or anti-RA33/RA36 antibodies. Anti-keratin antibodies correlate with disease severity and activity, and can appear early in RA or even before the onset of clinical manifestations. Therefore, it is meaningful for early diagnosis and prognosis of RA.
7.Anti-streptococcal wall polysaccharide antibody (ASP)
This test is designed based on the principle that streptococcal cell wall antigen and human heart valve glycoprotein have common antigenicity. The test has good sensitivity and specificity for the diagnosis of rheumatic fever, and the target organ of ASP in detecting the activity of rheumatic fever is the heart valve, i.e. whether there is rheumatic inflammation in the heart valve.
8, peripheral blood lymphocyte procoagulant activity test (PCA)
This test is designed according to the principle that when the sensitized lymphocytes are exposed to the same antigen again, thrombin-like substances can appear on their surface, which can promote coagulation. Professor Yu and others were the first to apply group A beta-hemolytic streptococcal membranes as a specific stimulant to stimulate peripheral blood lymphocytes in patients with acute rheumatic fever, and found that their coagulation activity was increased, and the degree of increase was more significant in patients with rheumatic fever than in other diseases. After 15 years of clinical research and repeated validation and clinical application, it is believed that this test can be used as an indicator of cellular immunology for the diagnosis of rheumatic heart disease.
9.Anti-neutrophil cytoplasmic antibody (ANCA)
The corresponding target antigens of ANCA are serine protease PR3, MPO and some rare antigens such as elastase, which are serum markers of systemic vasculitis. Its clinical significance.
1, ANCA mainly exhibits two karyotypes.
① cytoplasmic type (c-ANCA): mainly associated with Wegener’s granulomatous vasculitis;
② Perinuclear type (P-ANCA) is mainly seen in microscopic polyangiitis, Churg-Strass syndrome and oligoimmune deposition type segmental necrotizing glomerulonephritis and crescentic nephritis.
2, ANCA is valuable for both differential diagnosis and prognostic estimation of vasculitic disease, and is an important indicator of disease activity. ANCA titers are elevated at the onset (recurrence) of the patient. Some studies have shown that c-ANCA can be elevated 4-fold 2-5 weeks prior to vasculitis recurrence. Therefore, c-ANCA can be used as a predictor of relapse. c-ANCA titers can distinguish relapse from other causes (e.g., infection) of worsening disease.
10.Anti-SSA and anti-SSB
These two antibodies are named because they are associated with dry syndrome (SjÖgren syndrome, SS). Although these two antibodies are related to SS, they are also present in other connective tissue diseases. The positive rates of anti-SSA and anti-SSB antibodies in primary SS patients are 60% and 40%, respectively, and anti-SSB antibodies are more specific than anti-SSA antibodies for the diagnosis of dry syndrome. Anti-SSA and anti-SSB antibodies can cause congenital heart disease such as neonatal lupus and infantile heart block. Patients positive for anti-SSA and anti-SSB often have clinical manifestations such as vasculitis, lymph node enlargement, leukopenia, photosensitivity, skin lesions, and purpura.
11.HLA-B27
HLA is the acronym for human leukocyte antigen. Most of the seronegative spondyloarthropathies are closely related to HLA-B27, especially with ankylosing spondylitis has a strong correlation, about 90% of patients with ankylosing spondylitis are HLA-B27 positive. Therefore, the HLA-B27 test has a reference value for the diagnosis of ankylosing spondylitis, especially for cases with high clinical suspicion. However, because about 10% of patients with ankylosing spondylitis are HLA-B27 negative, a negative HLA-B27 test cannot exclude the disease. However, detection of HLA-B27 positivity does not confirm the diagnosis of ankylosing spondylitis because only 20% of the population with HLA-B27 positivity has ankylosing spondylitis. HLA-B27 is also important in the diagnosis of undifferentiated spondyloarthropathies. HLA-B27 is inherited from parents, is carried throughout life, and does not change with treatment.