[Migration of T-lymphocyte precursors into the thymus and the factors affecting this process]

Migration of FITC-labeled mouse bone marrow cells into the thymus was measured by flow cytometric analysis 3 hours after intravenous injection of cells into irradiated mice. The percentage of cells reaching the thymus diminished when the dose of injected cells increased. The dependence of the number or labeled cells in the thymus on the dose of injected cells was not linear. Pretreatment of cells with anti-SC-I serum, peanut lectin or H-2 incompatibility antigen abolished thymus migration, while treatment with anti-Thy-I serum, soybean lectin, trypsin or Thy-I-incompatibility antigen diminished cellular migration and treatment with neuraminidase enhanced it. It was concluded that the main type of migrating cells is SC-1+ precursors of T-lymphocytes. Penetration of these cells through the blood-thymus barrier is based on the recognition of their partly sialized surface glycoprotein receptors by membrane lectins of the blood-thymus barrier cells.