ARE T-CELLS FROM HEALTHY HEART REALLY ONLY PASSENGERS - CHARACTERIZATION OF CARDIAC TISSUE T-CELLS

Numerous studies have dealt with the occurrence of dendritic cells in various nonlymphoid organs such as kidney, liver or heart, whereas lym phocyte patterns in these organs have not been analyzed in detail. In the present study, leukocytes were quantified as cells/mm(2) in the pe rivascular, interstitial and parenchymal tissue sections of normal hea rt. We measured an overall mean leukocyte count in normal heart tissue of 17.0 +/- 2.7 CD45(+) leukocytes/mm(2), 9.1 +/- 1.8 thereof being C D4(+) T-helper cells (T-h). By comparison, CD8(+) T-cytotoxic/suppress or cells (T-s) and CD14(+) macrophages each accounted for only similar to 2.5 cells/mm2, and CD20(+) B cells for only 1.3 cells/mm(2). These T cells were further characterized as either CD45RA(+) naive T cells or as CD45RO(+) memory T cells. Segmentation of the tissue as defined in Section 2 yielded an ascending number of CD45RO(+) memory T cells f rom perivascular (0.4 +/- 0.2 cells/mm(2)) through parenchymal (12.8 /- 3.0 cells/mm(2)) to interstital (21.0 +/- 5.3/mm(2)). By contrast, the number of CD45RA(+) and Leu-8(+) cells decreased from perivascular to parenchymal. Peripheral T cells showed a reverse pattern of CD45RA /CD45RO antigen expression. Only similar to 3% of T cells expressed ac tivation markers IL-2R and IL-7R. Our data demonstrate that the majori ty of T cells in normal heart tissue are resting memory tissue T cells and not contaminating T cells from the peripheral blood. The increase in CD45RO(+) cells from perivascular to parenchymal with a correspond ing decrease in CD45RA(+) and Leu-8(+) heart-tissue T cells argues in favor of T-cell traffic in normal heart tissue.