title: Natural killer-type lysis of thymocytes from young mice by normal spleen cells in vitro.
abstract: Normal spleen cells from 6- to 10-week-old mice, enriched for natural killer (NK) cells on a discontinuous polyvinylpyrrolidone-silica (Percoll) gradient, lyse thymocytes of young mice (less than or equal to 19 days old) in a short-term 51Cr release assay. The highest NK-type activity was found in band 3 (density less than or equal to 1.077 g/ml) of a four-step gradient. In some experiments band 2 (density less than or equal to 1.070 g/ml) also showed NK activity. Activity was not unequivocably detectable in cells before separation or in bands 1 and 4. These results also show that the thymocyte sensitivity is dependent on the age of the target cell. Sensitivity of very young thymocytes (less than or equal to 7 days old) was higher than that of thymus cells from 8- to 19-day-old donors. Moreover, it seemed that syngeneic target thymocytes were lysed more effectively than allogeneic. Thus, an NK-type cell population may have the ability to lyse immature thymic target cells at an early stage of their differentiation. This could be of importance as a physiological mechanism for controlling the T cell repertoire and its reactivity.
mesh_terms: D000375:Aging; D000818:Animals; D002469:Cell Separation; D002470:Cell Survival; D003602:Cytotoxicity, Immunologic; D005260:Female; D007519:Isoantigens / Q000235:genetics; D007694:Killer Cells, Natural / Q000276:immunology*; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013045:Species Specificity; D013154:Spleen / Q000166:cytology* / Q000502:physiology; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology* / Q000502:physiology
chemical_list: D007519:Isoantigens