INFLUENCE OF CELL SURFACE GALACTOSYL DETERMINANTS ON SPLENIC LOCAUZATION OF MOUSE THYMOCYTES

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Abstract
Suspensions of mouse thymocytès are known to contain at least two antigenically and functionally distinct subpopulations of cells, one of which, after i.v. injection into syngeneic hosts, tends to localize in the spleen. Our experiments suggest that galactosyl determinants on the thymocyte cell surface may play a role in this splenic localization: (1) Thymocytes were aggregated in vitro with peanut agglutinin (PNA) (specific for galactosyl determinants) and the aggregated suspension was filtered through tightly packed cotton-wool columns; the effluent cells showed reduced agglutination by PNA and a parallel decrease in splenic localization in syngeneic hosts. (2) Thymocyte suspensions reacted with subagglutinating concentrations of peanut lectin showed markedly decreased syngeneic splenic localization after tail vein injection. (3) Thymocytes treated in vitro with galactose oxidase retained viability, but became unagglutinable by peanut lectin; such cells also showed markedly decreased localization to syngeneic spleens. (4) The subpopulation of thymocytes resistant to agglutination with peanut lectin may consist largely of non-dividing cells, since it incorporated much less iododeoxyuridine (IUdR) than the parent suspension. These studies affirm the importance of cell surface oligosaccharide ligands in lymphoid cell migration, and suggest a possible mechanism for the different specific organ localization patterns of the rapidly dividing thymocyte and its more mature nondividing counterpart.