Phenotype of the terminal transferase‐positive cells in human foetal liver and bone‐marrow: Analysis with monoclonal antibodies

Publisher Website
Google Scholar
Abstract
Liver and bone‐marrow of 20 human foetuses between 15th and 20th week of gestational age were examined. Mononuclear cells were labelled with murine monoclonal antibodies to reveal surface antigens and with a rabbit antiserum to TdT for the detection of the nuclear enzyme, using a double colour indirect immunofluorescence technique. The results have revealed that TdT+ cells express the phenotype of B cell precursors HLA‐DR+, CALLA+, FMC8+, LEU‐1‐, LEU‐5‐, LEU‐9‐‐. It suggests that foetal liver and bone‐marrow have an active function in B‐lymphopoie‐sis in humans. The involvement of TdT in the process of B‐cell immunological acquisition is uncertain because only humans and Xenopus embryos, among the species examined, express TdT outside the thymus during ontogenesis.