Antibodies IgA, IgM, IgG to Chlamydia trachomatis in the blood
Last reviewed: 23.04.2024
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Diagnostic antibody titer to Chlamydia trachomatis in the blood: for IgM - 1: 200 and above, for IgG - 1:10 and above.
During an acute Chlamydia infection and soon after it there is an increase in the titer of antibodies IgA, IgM and IgG to Chlamydia trachomatis in the blood. Infected Chlamydia trachomatis organism synthesizes antibodies, however these antibodies have a weak protective effect: usually pathogens persist even in the presence of high antibody titers. Early intensive treatment can inhibit the synthesis of antibodies. Due to the relatively large "antigenic mass" of chlamydia in genital infections, serum IgG antibodies are detected quite often and in high tiers. So, in children with chlamydial pneumonia they can be very high: 1: 1600-1: 3200.
IgM antibodies are detected in the acute period of infection (already 5 days after its onset). The peak of antibodies IgM falls on 1-2 weeks, then there is a gradual decrease in their titer (as a rule, they disappear after 2-3 months even without treatment). Antibodies of the IgM class are directed against the lipopolysaccharide and the main protein of the outer membrane of chlamydia. The presence of antibodies IgM indicates the activity of chlamydia. IgM antibodies do not penetrate the placenta, they are synthesized even in the fetus and belong to the own antibodies of newborns. Their presence indicates infection (including intrauterine) and indicates an active process. The titer of IgM-AT can increase with reactivation, reinfection or superinfection. The period of their half-life is 5 days.
Antibodies of class IgA are synthesized to the main protein of the outer membrane and a protein with a molecular weight of 60 000-62 000 chlamydia. They are detected in the blood serum 10-14 days after the onset of the disease, their titer usually decreases by 2-4 months as a result of successful treatment. When reinfected, the IgA antibody titer increases again. If after the course of treatment the IgA antibody titer does not decrease, it indicates a chronic or persistent form of infection. The detection of a high titer of antibodies of IgA class often indicates a pronounced autoimmune process in a patient, most often seen in patients with Reiter's syndrome. In such patients, the presence of IgA antibodies indicates a severe course of the disease.
IgG antibodies appear 15-20 days after the onset of the disease and can persist for many years. Reinfection is accompanied by an increase in the existing titer of antibodies of IgG class. Determination of antibody titer to chlamydia in the blood should be carried out in dynamics, the evaluation of research results based on a single study is unreliable. IgG antibodies penetrate the placenta and form anti-infectious immunity in newborns. High IgG-AT titers protect the fetus from infection, as well as women, from the appearance of salpingitis after abortion; In addition, they provide short-term protection (up to 6 months) from repeated infection with chlamydia. The half-life of IgG-AT is 23 days.
To establish the diagnosis it is necessary to simultaneously determine antibodies of classes IgA and IgG, with an unclear result of IgA - to further investigate antibodies IgM.
Newborns and their mothers are examined 1-3 days after birth, in case of a negative result in the presence of a clinical picture of the disease - again on the 5-7th and 10-14th days. The presence of antibodies of class IgM at repeated research, testifies to a congenital infection (parent antibodies of class IgM through a placenta do not penetrate). The absence of antichlamydial antibodies in newborn babies does not mean absence of chlamydial infection.
Determination of the antibody titer to Chlamydia trachomatis in the blood is an auxiliary test for the diagnosis of chlamydia, since antibodies are not detected in 50% of patients with chlamydia due to low immunogenicity.
The determination of antibodies of classes IgA, IgM and IgG to Chlamydia trachomatis in the blood is used for the diagnosis of chlamydia infection in the following diseases:
- urethritis, prostatitis, cervicitis, adnexitis;
- pneumonia, inflammatory diseases of the lungs;
- Reiter's disease, Behcet's syndrome, infectious arthropathies.
Diseases caused by Chlamydia trachomatis
Trachoma. Chronic keratoconjunctivitis, begins with acute inflammatory changes in the conjunctiva and the cornea and leads to scarring and blindness.
In scrapings from the conjunctiva, the fluorescence method determines chlamydial antigens in epithelial cells. More often they are found in the early stages of the disease in the upper part of the conjunctiva.
Urogenital chlamydia and conjunctivitis. The frequency of detection of chlamydia in men with non-gonococcal urethritis is 30-50%. The infection of women with the first pregnancy reaches 5-20%, which makes abortion - 3-18%. Among patients with signs of cervicitis, chlamydial infection is detected in 20-40% of cases; salpingitis - in 20-70% of cases; urinary tract infection - in 5-10% of cases.
Fitz-Hugh-Curtis syndrome is also attributed to early complications of chlamydial infection, it is acute peritonitis and perihepatitis, accompanied by ascites.
Chlamydia infection of the respiratory tract . In adults with chlamydial conjunctivitis, the symptoms of upper respiratory tract infection (pharyngitis, rhinitis, otitis, etc.) often appear, apparently developing as a result of the spread of chlamydial infection through the nasopharyngeal canal. Pneumonia in adults usually does not develop. In newborns infected from mothers, after 2-12 weeks after childbirth, the respiratory system may be affected, up to pneumonia.
Syndrome (disease) Reiter For Wright's Syndrome. Typical of the classical triad: urethritis, conjunctivitis and arthritis. This syndrome of chlamydia can be detected in the synovial fluid. An increase in the titer of antibodies of classes IgA, IgM and IgG in the course of development of active infection of joints is noted.
Endocarditis. Clinically proceed lightning fast, with significant damage to the valves of the aorta.
Latent infection can manifest spontaneously in the form of a low-symptom complication. More than half of the patients have signs of chronic prostatitis and / or sakroileitis.
Currently, for the diagnosis of Chlamydia infection methods are used to detect the antigens Chlamydia trachomatis in the study material (ELISA, fluorescent antibody method, PCR). Determination of antibody titer in blood serum to Chlamydia trachomatis is an auxiliary method for diagnosing chlamydia.
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