title: Qualitative and quantitative heterogeneity in Pgp-1 expression among murine thymocytes.
abstract: A proportion of Pgp-1+ cells in the thymus have been shown to have progenitor activity. In adult AKR/Cum mice the total Pgp-1+ population in the thymus differs from that of the bulk of thymocytes and is antigenically heterogeneous when examined by flow cytometry. Pgp-1+ thymocytes are enriched for several minor cell populations compared to total thymocytes: B2A2-, interleukin-2-receptor+ (IL-2R+), and Lyt-2-, L3T4-. However, these subsets are still a minor proportion of the Pgp-1+ cells, the majority being Lyt-2+ and/or L3T4+ and B2A2+. Pgp-1+ thymocytes also differ from the bulk of thymocytes in having lower amounts of Thy-1 and in showing a higher proportion of single positive (Lyt-2+, L3T4- or Lyt-2-, L3T4+) cells. Populations of adult thymocytes that are enriched in progenitor cells can be isolated by cytotoxic depletion using either anti-Thy-1 antibody (Thy-1 depletion) or anti-Lyt-2 and anti-L3T4 antibody (Lyt-2, L3T4 depletion). Pgp-1+ cells in progenitor cell-enriched populations are also phenotypically heterogeneous. Pgp-1+ cells in both populations may be IL-2R+ or IL-2R- and B2A2+ or B2A2-. The population of Pgp-1+ cells in progenitor cell-enriched populations in the adult differs from that of the fetus at 14 days of gestation in that in the 14-day fetus, most Pgp-1+ cells are IL-2R+. By Day 15 of gestation, distinct populations of Pgp-1+, IL-2R-; Pgp-1+, IL-2R+; and Pgp-1-, IL-2R+ cells are observed. In the 15-day fetus, as in the adult, many Pgp-1+ thymocytes express low to moderate levels of Thy-1. The total percentage of Pgp-1+ cells in the thymus varies among different mouse strains, ranging from 4 to 35% in the thymus of young adult mice. Pgp 1.1 strains contain more detectably Pgp-1+ thymocytes than Pgp 1.2 strains; however, there is variability in the proportion of Pgp-1+ cells, even among Pgp 1.2 strains. In contrast to AKR/Cum mice, the Pgp-1+ thymocyte population in BALB/c mice, which contain a high proportion of Pgp-1+ thymocytes, closely resembles the total thymocyte population.
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D000950:Antigens, Ly / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis*; D002469:Cell Separation; D002470:Cell Survival; D005260:Female; D005865:Gestational Age; D007958:Leukocyte Count; D008562:Membrane Glycoproteins / Q000032:analysis*; D051379:Mice; D008806:Mice, Inbred AKR; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010641:Phenotype; D011247:Pregnancy; D016201:Receptors, Lymphocyte Homing; D013234:Stem Cells / Q000276:immunology; D013601:T-Lymphocytes / Q000145:classification* / Q000276:immunology / Q000502:physiology; D018800:Thy-1 Antigens
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000950:Antigens, Ly; D000954:Antigens, Surface; D008562:Membrane Glycoproteins; D016201:Receptors, Lymphocyte Homing; D018800:Thy-1 Antigens