Late persistent expressions of ICAM-1 and VCAM-1 on myocardial tissue in children with lymphocytic myocarditis

Both intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) have been implicated in cardiac allograft rejection. However, there is little information about the relationship between the expression of these adhesion molecules and myocarditis in children.

Immunoreactivities of ICAM-1 and VCAM-1 were examined by enzyme immunoassay in 31 biopsy specimens obtained from 11 pediatric patients with biopsy-proven myocarditis or cardiomyopathy. Five of the 11 patients had clear evidence of acute myocarditis. The other 6 had ECG abnormalities identified by mass screening for heart disease, and subsequently had been histologically diagnosed as having non-specific cardiomyopathy. The period between onset of myocarditis or identification of ECG abnormality and immunohistochemical studies was 23 to 60 days and 8 months to 3 years, respectively. Expression of ICAM-1 and VCAM-1 was assessed by counting ICAM-1 and VCAM-1 positive vessels and dividing by the total number of vessels. ICAM-1 was significantly present on 81% (P < 0.01) of myocardial tissue samples in the 5 patients with healing-stage acute myocarditis, and on 45% (P < 0.05) in the remaining 6 patients with non-specific cardiomyopathy, compared with 24% in control specimens obtained from right ventricular muscle resected at surgery for tetralogy of Fallot. VCAM-1 was also present on 50% (P < 0.05) of the samples from the 5 patients with acute myocarditis, but was not present in those with non-specific cardiomyopathy.

This persistent expression of ICAM-1 suggests that myocardial cell damage may persist immunologically for a long period in myocarditis. In addition, immunostaining for these adhesion molecules may be diagnostic value in clinically silent lymphocytic myocarditis and chronic cardiomyopathy.