A Repopulation Assay For B and T Lymphocyte Stem Cells Employing Radiation Chimaeras

Publisher Website
Google Scholar
Abstract
The repopulation of the peripheral lymphoid compartment of lethally-irradiated rats reconstituted with lymphopietic stem cells was studied. Cell lineages were traced by using genetic markers of cell surface molecules as follows: Ig allotype for B lymphocytes and peripheral T cell alloantigen for T lymphocytes. Provided the markers had been bred on to a genetic background congenic with the hosts, they conferred neither an advantage nor disadvantage in competition with unmarked cells. The degree of chimaerism measured the lymphopoietic activity of the restorative inoculum. The most potent activity was found in fetal liver and spleen, next in infant spleen and bone marrow, finally in young adult bone marrow. Peripheral lymphoid tissues showed very little activity; thymus cells were inert. This tissue distribution, the stability of the chimaerism and the substantial expansion of numbers from the injected cells all point to the assay measuring an early stem cell. The overlap of sub-populations of lymphocytes in the rat thoracic duct was studied. A method for the conjugation of fluorescein to antibodies while they are attached to immunoadsorbent affinity columns is also described.
Keywords