Immunological aspects in patients with acute myocardial infarction

In order to elucidate the immunological aspects of acute myocardial infarction (AMI), we studied lymphocyte subpopulations, immunoglobulin levels, and natural killer (NK) cell activity in 21 patients serially after admission within 24 h of AMI onset. The percent T cells, T cell count, and percent CD4-positive cells were significantly decreased on the 1st hospital day, compared to days 7 and 28. The CD4/CD8 ratio on the 1st day was also significantly lower than on day 7, and was significantly lower than that of normal subjects. Natural killer (NK) cell activity and serum immunoglobulin G (IgG) levels showed substantial decreases each test day, compared with those in normal subjects. However, there were no significant serial changes in the percent B cells, the B cell count, or in the serum IgG, IgA, or IgM levels. Thus, not only T cell function, but also immunoglobulin levels and NK cell activity were depressed in the acute stage of myocardial infarction. Therefore, active measures should be taken to prevent infection in the acute stage of myocardial infarction in which invasive procedures such as insertion of indwelling catheters are often necessary.