The immune system plays an important role in the formation of an adequate immune response during transplantation of allogeneic bone marrow. The aim of the study was to study the localization of CD8-positive cells in the lymph nodes at the early stages after the venous injection of a suspension of allogeneic bone marrow cells. The experiments were carried out on 50 outbred male rats. The animals were divided into three groups: group 1 - intact rats (n=10), group 2 - control animals (n=10), which were injected 3 ml of 0,85% natrium chloride solution; 3rd group - experimental rats (n=30), which were injected into the tail vein with one ml of a cell suspension of bone marrow extracted from the epiphysis of the femur of another rat and mixed with 2 ml of 0,85% natrium chloride solution. Animals were withdrawn from the experiment after 40, 120 and 240 minutes from the start of the experiment. After 40 minutes from the start of allogeneic bone marrow transplantation in the lymph nodes, CD8+ lymphocytes are detected in the expanded subcapsular, paracortical zones, near the vessels, in the cortical sinuses, and in the medulla. After 120 minutes from the start of transplantation, the number of lymphoid nodules with different numbers of CD8+ lymphocytes and different intensity of their color increases. The reproduction of CD8+-lymphocytes occurs under the capsule in the cortex of some lymphoid nodules, the vessels dilate, fragmentation of the medulla occurs with the appearance of new groups of CD8+-lymphocytes. After 240 minutes from the start of allogeneic bone marrow injection, a small number of CD8+ lymphocytes are detected in the subcapsular zone, in the peripheral layer of single lymphoid nodules, along the lymphatic and blood vessels, and as groups in the medulla. There is a fatty degeneration of the medulla of the lymph nodes. Thus, based on the localization and reproduction of CD8+ lymphocytes in the lymph nodes, it can be assumed that the recognition of allogeneic bone marrow antigens occurs in the subcapsular zone, the peripheral layer of lymphoid nodules, and areas of the medulla.
