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Con A response and interleukin 2 receptor expression of thymocytes rosetting with phagocytic cells of the thymic
1INSERM U25, CNRS UA 122, Hopital Necker, Paris, France.
Thymocytes bind to the phagocytic cells of the thymic reticulum (P-TR) and spontaneously forming rosettes were isolated and characterized. Rosetting thymocyte subsets included cells expressing different surface phenotype: most of them (91%) were of the double positive L3T4+ Lyt-2+ phenotype; a minor subpopulation (2.4%) expressed the helper L3T4+ Lyt-2- phenotype and finally a small subpopulation (6.3%) was negative for both L3T4 and Lyt-2 markers. Although the rosetting thymocytes were not enriched in mature single positive cells as compared to the non rosetting population, they showed a higher responsiveness to ConA plus recombinant IL-2. Moreover the rosetting thymocytes were induced to express IL-2 receptors just after stimulation with ConA whereas co-stimulation with ConA plus IL-2 was essential for the generation of IL-2 receptors on the non rosetting and total thymocytes. The possibility that the rosetting thymocytes acquired this activity during the rosetting process is discussed.
Thymocytes bind to the phagocytic cells of the thymic reticulum (P-TR) and spontaneously forming rosettes were isolated and characterized. Rosetting thymocyte subsets included cells expressing different surface phenotype: most of them (91%) were of the double positive L3T4+ Lyt-2+ phenotype; a minor subpopulation (2.4%) expressed the helper L3T4+ Lyt-2- phenotype and finally a small subpopulation (6.3%) was negative for both L3T4 and Lyt-2 markers. Although the rosetting thymocytes were not enriched in mature single positive cells as compared to the non rosetting population, they showed a higher responsiveness to ConA plus recombinant IL-2. Moreover the rosetting thymocytes were induced to express IL-2 receptors just after stimulation with ConA whereas co-stimulation with ConA plus IL-2 was essential for the generation of IL-2 receptors on the non rosetting and total thymocytes. The possibility that the rosetting thymocytes acquired this activity during the rosetting process is discussed.