ABSTRACT
BACKGROUND: In this study, we investigated the early time course of expression of the major histocompatibility (MHC) antigens, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), interleukin-6 and the histopathological changes in the coronary arteries of cardiac allografts exchanged between inbred mice strains that differ in one loci of class I major histocompatibility antigen (B10.BR to B10.A). MATERIAL AND METHOD: No immunosuppressive therapy was used. Both allografts and the hearts of the recipients were harvested at 7 (group 1, n=6), 15 (group 2, n=6), 21 (group 3, n=6), and 30 (group 4, n=6) days after transplantation. They were examined by immunohistochemistry, microscopy and morphometry. All allografts had contractions at the time of harvest. RESULT: A strong MHC class I antigen expression was present on the endothelial and medial cells of the coronary arteries in group 1 and remained unchanged in the rest of the groups. However, MHC class II reactivity was none or very little at any time. Mild to moderate ICAM-1 expression was observed on the endothelial cells, but not on the medial cells at any time by 30 days. VCAM-1 expression was strong both on the endothelial and medial cells at any time. Moderate degree expression of interleukin-6 was observed from 7 to 30 day specimens. Histopathologically, percentage of affected vessels (vessels with intimal thickening) was less than 10 % in 7 day group and increased up to 50 % at 30 days. Mean percent narrowing of the lumen of the affected vessels revealed less than 20 % at 7 days and 40 % at 30 days. The area occupied by tropomyosin positive cells in the intimal lesion, graded from 0 to 3, showed gradual increase but remained between grade 0 to 1 by 30 days. Medial integrity was also well preserved at any time. Moderate perivascular mononuclear cell infiltration was observed at 7 days and it was progressively increased upto 30 days. Recipients' heart revealed no positive immunopathologic findings. CONCLUSION: In this study, the early time course of progression of the transplantation vasculopathy was demonstrated in the murine heterotopic heart transplant model.