Lymphocytic Subsets and Histopathologic Changes Associated with the Development of Heart Transplant Arteriosclerosis

Transplantation of vascularized organ allografts is associated with the development of arteriosclerosis in the vessels of the donor graft. We have recently examined the distribution of lymphocytic/mononuclear inflammatory cell subsets and histopathologic changes seen in the sequential development of transplant arteriosclerosis in cardiac allografts exchanged between inbred rat strain combinations (LEW-to-F344) that differ for weak histocompatibility loci. The donor grafts were harvested at 7, 14, 21, 28, 50 to 65, and 90 days after transplantation, and the vascular lesions were characterized for the immunopathologic changes associated with the chronic rejection of the grafts. The inflammatory cell infiltration of the graft myocardium was present as early as 7 days after transplantation (53.37 +/- 9.06 inflammatory cells/high-power field), and the accumulation of cells increased at 3 and 4 weeks after transplantation (112.12 +/- 16.58 and 130.40 +/- 21.24 cells/high-power field, respectively). The infiltrating inflammatory cells in the grafts at 4 weeks after transplantation were predominantly ED-1+ macrophages (63.39%), with a substantial number of OX19+ T lymphocytes (28%), OX8+ Tc/s cells (25.4%), 3.2.3+ natural killer cells (16.89%), W3/25+ Th cells (20.2%), and a small number of OX33+ B lymphocytes (1.13%) and interleukin-2 receptor+ T lymphocytes (2.6%). Among the T-cell population, most (87.6%) were positive (R73+) for T-cell receptors. The arteriosclerotic lesions present in the cardiac grafts exhibited a gradual increase in severity of the vascular intimal proliferation and a similar pattern of increased intensity of cellular infiltration. The lesions were infiltrated with inflammatory cells beginning in the first week and increasing for the first month after transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)