Aims-To examine the species specificity of the microimmunofluorescence test (MIF) and assess a time resolved fluoroscopic immunoassay (TRIA) for measuring IgG antibodies to C pneumoniae. Methods-Sera from 1020 subjects were tested by MIF for IgG, IgM, and IgA antibodies to C pneumoniae, C trachomatis, and C psittaci; 501 serum samples were also tested by TRIA for IgG antibodies to C pneumoniae. Results-C pneumoniae antibody titres as measured by MIF were correlated with those for C psittaci and C trachomatis. It was estimated that on average, one third of the twofold dilution steps that make up the final C pneumoniae antibody titre may be due to cross reacting genus specific antibody. The results of TRIA correlated well with those of MIF. In 75% of cases, the TRIA result predicted a three titre range within which the actual MIF result would fall. Conclusions-MIF does not appear to be as species specific as claimed. TRIA is unlikely to be as specific but as it is completely objective, easier to perform, amenable to automation, and gives reproducible results, it is a rapid and useful method for comparing populations. (J Clin Pathol 1999;52:99-102)
A multicenter prospective study was performed on 160 asthmatic adults suffering from acute episodes of bronchitis and 88 non‐asthmatic controls, to investigate potential associations among Chlamydia pneumoniae infection and/or anti‐C. pneumoniae heat shock protein 10 antibodies, and asthma. We used micro‐immunofluorescence to detect serum anti‐C. pneumoniae IgG, IgA and IgM antibodies and enzyme‐linked immunosorbent assay to detect serum anti‐Chsp10 peptide IgG antibodies. The serological prevalence of C. pneumoniae was 73.1%. An association was observed between the presence of anti‐Chsp10 antibodies and adult onset asthma. The humoral immune responses were not confined to any particular region of the Chsp10 protein.
The humoral immune response to Chlamydia trachomatis10-kDa heat shock protein (Chsp10) in populations of Russian and French origin was studied by using a recombinant Chsp10 enzyme-linked immunosorbent assay. A physiological but not a serological correlation of Chsp10 exposure with Chsp60 exposure was observed in the Russian population. In the French population studied, there was a significant association between detection of anti-r-Chsp10 immunoglobulin G (IgG) antibodies and chronic genital tract infections. Chsp10 residues 50 to 67 were found to contain an immunodominant although not universal B epitope. Cross-reactions with Chlamydia pneumoniae orEscherichia coli GroES protein are limited but may occur. Our study suggests that detection of anti-Chsp10 IgG antibodies is associated with chronicity of C. trachomatis genital tract infection and does not parallel that of anti-Chsp60 IgG antibodies.
Chlamydia trachomatis heat shock protein 10 (Chsp10) is associated with chronic genital tract infection with C. trachomatis. Chsp10 is homologous to human chaperonin 10 (Cpn10) and early pregnancy factor (EPF), a form of human Cpn10 that is specifically secreted at the start of pregnancy. We investigated cross-reactions between serum anti-Chsp10 antibodies and anti-EPF antibodies in pregnant and nonpregnant patients. Pregnancy was found to be associated with the presence of anti-EPF antibodies, which are specifically induced in pregnant women with a history of C. trachomatis infection, and with the presence of serum anti-Chsp10 antibodies. We also found that infertility was associated with the presence of anti-Chsp10 and anti-EPF antibodies. The HLA class II haplotype DR8 DQ4 was associated with the presence of anti-Chsp10 antibodies but not of anti-EPF antibodies.Heat shock proteins (Hsps) are a highly conserved group of polypeptides that are produced under a variety of stress conditions to preserve cellular functions. The major Hsps are molecular chaperones that direct the folding and assembly of polypeptides in the cell (11). Early pregnancy factor (EPF) has been identified as a homologue of chaperonin 10 (Cpn10). It belongs to the heat shock protein family, but unlike other members of this family, EPF is detected outside the cell. EPF has immunosuppressant (17) and growth factor properties (19), rendering it essential for the growth and survival of the embryo during the pre-and postimplantation periods (2, 3). The passive immunization of pregnant mice with anti-EPF antibodies leads to the retardation of embryonic development and/or inhibition of implantation.The partial amino acid sequences obtained for platelet-derived EPF are 100% identical to the corresponding sequences of human mitochondrial Cpn10 (8, 14) and 33.3% identical to those of the Chlamydia trachomatis chlamydial Hsp 10 (Chsp10) (12) (Fig. 1). The 10-kDa Hsp of C. trachomatis has been shown to be associated with chronic infection and sequelae, such as ectopic pregnancy (4). Hsp synthesis is induced in microbial pathogens during infection (6). Microbial Hsps are highly immunogenic and display a high level of conservation through evolution; in addition, immune cells have been shown to recognize both microbial and self-Hsp (22). Therefore, cross-reactions may occur between C. trachomatis Chsp10 and human extracellular EPF. Such cross-reactions might interfere with EPF function at the start of pregnancy, thereby playing a role in C. trachomatis-associated female infertility.We studied a population of 716 women in the first trimester of pregnancy. We used a C. trachomatis-specific molecular biology detection technique and investigated C. trachomatis species-specific and Chsp10-specific serum antibody responses. We tested 230 of the patients for immunoglobulin G (IgG) antibodies specifically recognizing two EPF-derived synthetic peptides. As EPF is essential for embryo implantation and survival, we also investigated a population of 210 women consulti...
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