title: Expression of asialo GM1 on a subset of adult murine thymocytes: histological localization and demonstration that the asialo GM1-positive subset contains both the functionally mature and the proliferating thymocyte subpopulations.
abstract: A small population (10 to 14%) of adult murine thymocytes expresses the glycolipid asialo GM1 (aGM1). Flow cytometric analysis of the aGM1+ cells present in thymus demonstrates the expression of a mature or medullary phenotype by 50% of the aGM1+ cells. Analysis of cytotoxic T lymphocyte precursor activity, proliferative capacity, and IL 2 production displayed by aGM1+ and aGM1- thymocyte fractions isolated by cell sorting indicates that these functional compartments of the thymus are contained within the aGM1+ subset. The aGM1+ population also contains virtually all mitotically active thymocytes, as measured by incorporation of bromodeoxyuridine. The immature IL 2 receptor-bearing thymoblasts are also included in the aGM1+ population. Immunohistochemical labeling of thymic tissue sections reveals that the majority of aGM1+ cells are located in the medulla. Clusters of aGM1+ cells are found scattered throughout the cortical and subcapsular areas. The aGM1+ population therefore contains the functionally mature thymocytes as well as some immature thymocytes, particularly those that are mitotically active. It is suggested that the aGM1+ subset of thymocytes represents those cells that are mature or actively maturing. This hypothesis is discussed in the context of current concepts of intrathymic T cell differentiation pathways.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D002453:Cell Cycle; D002454:Cell Differentiation; D002455:Cell Division; D005434:Flow Cytometry; D005677:G(M1) Ganglioside; D006028:Glycosphingolipids / Q000378:metabolism*; D037102:Lectins; D051379:Mice; D008815:Mice, Inbred Strains; D019887:Peanut Agglutinin; D011971:Receptors, Immunologic / Q000032:analysis; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D000954:Antigens, Surface; D006028:Glycosphingolipids; D037102:Lectins; D019887:Peanut Agglutinin; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D005677:G(M1) Ganglioside; C018835:asialo GM1 ganglioside