Functional abnormalities of circulating natural killer cell subpopulations in patients with dilated cardiomyopathy.

We investigated abnormalities in natural killer (NK) cells in the myocardium and circulating blood of 38 patients with idiopathic dilated cardiomyopathy (DCM), 18 patients with hypertrophic cardiomyopathy, 8 patients with primary amyloidosis, and 12 age-matched normal control subjects. Immunohistochemical staining of myocardial biopsies revealed a significantly greater number of CD57-positive NK cells in patients with DCM than that in controls (3.7 +/- 2.7 v.s. 1.9 +/- 1.6, p < 0.05). The New York Heart Association functional class, left ventricular ejection fraction, myocardial fiber diameter, and interstitial fibrosis volume fraction did not differ significantly between the DCM patients who died within five years of diagnosis and the 31 surviving DCM patients. However, there were significantly fewer CD57-positive NK cells in patients who died than in surviving patients (p < 0.05). There were no significant differences in the peripheral NK cell activity or the number of NK subset cells between the 16 patients with DCM (n = 16) and the 12 age-matched normal controls. In normal controls, the number of some NK cell subpopulations (CD16+, CD57+, CD16+ CD57+, and CD8+ CD57+ cells) were positively correlated with NK cell activity. In patients with DCM, there was no correlation between the number of NK cell subpopulations and NK cell activity. Our findings indicate that functional abnormalities exist in NK cell subpopulations in patients with DCM, and that these abnormalities may be related to the pathogenesis of DCM.