title: Separation of newborn BALB/c thymocytes by a density gradient method.
abstract: The recognition of T-lymphocyte subpopulations has led to a search for methods to separate lymphoid subsets on the basis of physical, biochemical and biological differences. The analysis of these properties of thymic cells made it possible to distinguish two main subsets: a major population of immunologically inactive cells, and a minor subpopulation of immunocompetent T cells. In the present paper a method for the separation of thymic lymphoid cell subpopulations in mice aged 5 to 10 days is reported. The cells resulting from this procedure were analyzed according to different criteria. From a morphological point of view, the existence of a large blast-like cell (termed I) and a smaller cell (termed III) was evident. These two cell subclasses were investigated in order to characterize their division rate, in vitro sensitivity to dexamethasone and peanut lectin agglutination pattern. It was found that subpopulation I had a faster division rate than subpopulation III, as measured in vitro by [3H]thymidine (dThd) incorporation and mitotic index with colchicine. When these different cells were incubated in the presence of dexamethasone at different concentrations, no significant difference was seen in [3H]dThd incorporation at the age of 5 days, while on the tenth day subpopulation I became more resistant to the hormone than subpopulation III. When incubated with peanut lectin, it was evident that subpopulation I was mainly constituted by PNA-unagglutinable cells. On the other hand, subpopulation III consisted mostly of PNA-agglutinable cells.
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation; D002469:Cell Separation / Q000379:methods*; D002499:Centrifugation, Density Gradient; D004247:DNA / Q000096:biosynthesis; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D037102:Lectins / Q000494:pharmacology; D008297:Male; D051379:Mice; D008940:Mitotic Index; D019887:Peanut Agglutinin; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D013950:Thymus Gland / Q000166:cytology
chemical_list: D037102:Lectins; D019887:Peanut Agglutinin; D003907:Dexamethasone; D004247:DNA