Objectives: The aim of this doctor thesis is to evaluate cell-mediated immunity of patients with acute myocardial infarction based on investigation of the presence and distribution of apoptotic molecule granulysin in peripheral blood lymphocytes, as well as estimation of their cytotoxic potential. Patients, material and methods: Patients with acute myocardial infarction with ST elevation (STEMI), who underwent primary percutaneous coronary intervention with continued drug treatment and patients with acute myocardial infarction without ST elevation (NSTEMI), who were treated with drug therapy according to the guidelines of the European Society of Cardiology were included in the investigation. Both groups of patients were involved in the program of early stationary medical rehabilitation. Healthy subjects, which were recruited during routine cardiac’s examination representd the control group. On days 1, 7, 14, 21 and on day 28 after the acute coronary event 10-16 ml of venous blood were taken from the patients for immunological and biochemical analyses. Mononuclear cells from peripheral blood were separated by centrifugation on a density gradient. Their phenotype was analysed by flow cytometry. Direct double-labeling of surface CD3 and CD56 markers was aplied in the combination with intracellular granulysin labeling by indirect immunofluorescence. Immunocytochemistry was used to visualize granulysin in peripheral blood lymphocytes. Immunohistology was implemented for detection of CD3 and CD56 antigens, granulysin, apoptotic protease activating factor 1 (APAF-1) and MHC class I molecules in paraffin embedded myocardial tissue sections from patients who died in the first and the fifth week after the acute coronary event, and from patients who died from non-cardiac causes. Flow cytometry with PKH26 test and anexin V was applied to analyse long term (18 hours) cytotoxicity (necrosis and apoptosis) of NK cells against K-562 targets in the presence of medium only, neutralizing antibodies directed towards perforin and/or granulizin. Age, gender, smoking habit, complete blood count and laboratory biochemical parameters (urea, creatinine, Na+, K+, aspartate aminotransferase (AST), alanine transaminase (ALT), creatine kinase (CK) and troponin I) were analysed in examinees. Ultrasound examination of the heart was performed in examinees at the beginning and at the end of rehabilitation period. Results: In patients with NSTEMI percentage of granulysin+ peripheral blood lymphocytes in all subpopulations, including both subsets of NK cells (CD56+dim and CD56+bright) was statistically significantly higher on days 1 and 7 after the acute coronary event when compared with control group while their lowest frequency was on the 14th day after the acute coronary event. In patients with STEMI percentage of granulysin+ lymphocytes including both subsets of peripheral blood NK cells was almost negligible on days 7 and 14 after the acute coronary event. Visualization of granulysin+ cells using immunocytochemistry in peripheral blood lymphocytes of patients with NSTEMI and STEMI was followed by the mean fluorescence intensities (MFIs), which were calculated with flow cytometry. In healthy subjects, peripheral blood NK cells in the 18-hour cytotoxicity assay spontaneously kill and induced apoptosis of target K562 cells, mainly using perforin mechanism. In patients with NSTEMI on days 7 and 28 after the acute coronary event the apoptosis of K 562 targets was statistically significantly decreased in the presence of anti-perforin antibody, anti-granulysin antibody or their combination, but without additive effect. In the same patients, the 14th day after acute coronary events the killing was significantly reduced and apoptosis becomes negligible due to the low frequency of granulizin+ NK cells. Increased percentage of granulysin+ NK cells on days 21 and 28 led to the higher apoptosis of K 562 cells in direct contact. In patients with STEMI apoptosis of K 562 targets was negligible on the 7th day due to low frequency of granulysin+ NK cells and MFI. Apoptosis, which was observed on 14th and on 21th day after the acute coronary event was only 1-10% and it could be removed with the addition of anti-perforin and anti-granulysin antibodies with additive effect, although each antibody itself did not cause statistically significant reduction. Expression of MHC class I molecules was significantly decreased in the center of the infarct necrosis, but MHC class I molecules were present in the area surrounding the necrosis and in the healthy myocardium. In the leukocyte infiltration, there were relatively rare CD3+ and CD56+ cells that expressed granulysin in paraffin embeded myocardium tissue sections from patients who died in the 1st week after the acute coronary event. CD3+ cells, CD56+ cells and granulysin+ cells were found in the vicinity of APAF-1+ cardiomyocytes, especially in areas with myocardial infarction and leukocyte infiltration, in contrast to patients who died in the fifth week after acute coronary event, where only APAF-1+ cells were present. Ultrasound examination showed mild recovery of ejection fraction at the end of rehabilitation period, although it was not statistically significant. Conclusion: Granulysin mediated apoptosis is, at least partially, involved in myocardial injury during and immediately after the acute coronary event, but granulysin could contribute to the resolution of the leukocytes and inflammatory response generated during ischemic endogenous pro-inflammatory response in the field of myocardial infarction