Background. The chlamydial infections are very frequently considered in the causal connection with some diseases e.g. atherosclerosis or chronic joint infections. The evidence of the antibodies against the heat shock protein of chlamydial origin is not the usual part of practical serological diagnostics. The aim of this study is an attempt to identify antibodies against the heat shock protein and other antigens of chlamydiae in the sera of two groups of patients and in the sera of blood donors. Methods and Results. The sera of patients suffering from unstable angina pectoris (NAP=69), sera of patients waiting for the application of endoprothesis due to coxarthrosis (EKK=49), and sera of 100 blood donors have been examined for antibodies against the heat shock protein, against the major outer membrane protein (MOMP) of C. pneumoniae, and against the chlamydial genus specific lipolysaccharides. The antibodies against the cHSP60 in the sera of patients suffering from NAP have been identified in 41 cases (59.4 %), in orthopaedic patients in 21 cases (42.9 %) and in 23of the blood donors (23% ). The difference of the antibody-occurrence in the sera of patients is significantly higher than in case of blood donors. The antibodies against the MOMP of C. pneumoniae prevailed in all sera of the persons examined. Their occurrence in the IgG class had a high statistical frequency. The genus specific positive reaction occurred more frequently also in the sera of the probands that reacted positively against the cHSP60 than in those negatively reacting. According to our results, the significance of C. pneumoniae in the genesis of the antibodies against of cHSP60 can be concluded. Conclusions. The proof of the anti-cHSP60 antibody and of the species-specific chlamydial antibodies may be a useful contribution to the exact diagnosis of the disease with possible chlamydial participation. The C. pneumoniae infection was probably of the main importance for the origin of the anti-cHSP60 antibody in examined persons.

        Key words: C. pneumoniae, serology, chlamydial heat shock protein (cHSP60), unstable angina pectoris, endoprothesis, blood donors.