ИСТИНА

Histocompatibility class II molecules (HLA-DR) positive cells represented mostly by macrophages, dendritic cells and B-lymphocytes can orchestrate and affect inflammatory responses in atherosclerotic lesions. We have recently demonstrated the HLA-DR cells in normal (grossly uninvolved) human aortic intima. In present study we investigate phenotypical and morphological characteristics of subendothelial intimacytes expressing HLA-DR. Intimal en face preparations of grossly normal aorta were used for investigation. Visualization of antigens was carried out using confocal laser scan microscopy and immunohistochemical methods. For the quantitative measurements isolated subendothelial intimacytes were analyzed using a flow cytofluorimeter. Four main morphotypes of HLA-DR cells have been identified: 1) large stellate cells (more than 20
m) possessing two or more rounded processes; 2) round and irregular-shaped cells over 10
m in size; 3) small round-shaped cells less than 10
m in size; 4) minor subpopulation was presented by stellate cells with polygonal body and sharped processes that were situated parallel to endothelium. Over 90% of first population and almost all cells of second and third subpopulations expressed CD45 indicating their monocyte origin. Cells of fourth subpopulation were negative for CD45 but some contain alpha actin. The processes of these cells interact with other cells of a similar shape that expressed alpha actin but not HLA-DR.Thus intimal antigen-presenting cells have different origin. Immune response in subendothelial intima may result from differentiation and activation of resident non-blood intimacytes. Antigen-presenting function of resident intimacytes suggests unknown mechanisms of adaptive immune response.