Chlamydia pneumoniae (C. p.) is very frequently cited as an important factor of the origin of atherosclerosis. To confirm the diagnostic value of the serological examination the following reactions have been used: microimmunofluorescence reaction (MIF) for estimating of antibodies against major outer membrane proteins C. p. (anti-MOMP) and ELISA for detecting antibodies against the lipopolysacharides of C. p. (anti-LPS), both in IgA and IgG immunoglobulin classes of the serum. The ELISA for the detection of the IgG antibodies against chlamydial heat shock protein (cHSP60) has been used. The sera of 155 patients suffering from acute myocardial infarction (AMI) and 69 patients with unstable angina pectoris (UAP) have been examined. The heart disease has been confirmed by anamnesis, electrocardiography and coronarography. As a control group the sera from 112 persons without sings of a heart disease were examined. The antibodies against the cHSP60 have been determined only in the sera 69 patients with UAP and 49 control sera. Statistically higher occurrence of the antibodies anti-MOMP C. p. in the IgA class sera of patients suffering from UAP has been noted compared with those found in the sera of the control group (χ2 = 18.56; p < 0.01). In the globulin IgG class of the both groups no difference has been found. The anti-LPS C. p. antibodies in the IgA as well in IgG anti-LPS classes of the patients sera with UAP were present significantly more frequently than in the control group (χ2 = 11.49; p < 0.01, χ2 = 4.16; p < 0.05). Similarly the incidence of the anti-LPS C. p. antibodies in the IgA class sera of 155 patients suffering from AMI was significantly higher than in the control group (χ2 = 8.55; p < 0.01). The anti-cHSP60 antibodies have been found in 41 out of 69 patients suffering from UAP (59.4%) and in 21 of 49 control individuals (42.9%). The results seem to confirm an important role of C. p. in atherogenesis. The monitoring of the antibodies against the C. p. may supplement the diagnostics in patients suffering fromUAP and AMI and the efficacy of its therapy and prevention as well.

        Key words: atherogenesis – cardiovascular diseases – Chlamydia pneumoniae – HSP60.