Murine thymocytes with ability to inhibit IL-2 production. II. Characterization of a subpopulation with regulatory function in the thymus.
Studies were performed to characterize the thymocyte subset responsible for the efficient inhibition of spleen cell interleukin-2 (IL-2) production. By different cell separation techniques, C-mediated cytotoxicity, immunoabsorbance, and cell sorting by flow cytometry, we have identified two phenotypically distinct subpopulations of thymocytes. One subset, belonging to the minor population (3-5%) of the CD4-CD8-, i.e., double-negative thymocytes, is defined as the subset from which the suppressive thymocytes are generated. After 28 hr of Con A stimulation, these cells undergo a phenotypical change in vitro and generate a population exerting the inhibitory effect. This latter subset inhibits 95-99% of the IL-2 produced by spleen cells and is characterized by expressing the CD8 antigen, high levels of HSA, low levels of CD3, and being IL-2R positive (HSA+CD4-CD8+CD3lowIL-2R+). Based on the experiments where stimulated CD4+CD8+, i.e., double-positive thymocytes, failed to suppress IL-2 production, we conclude that the CD8+ immature single-positive thymocytes are generated directly from the DN subset as an intermediate stage to the DP cells. When CD8(+)-stimulated thymocytes were enriched, the suppression was efficient even at thymocyte:spleen cell ratio of 0.01:1. It is suggested that this subpopulation of thymocytes may serve as a regulatory set of cells during critical stages of thymic maturation.
Gigliotti
D
D
Department of Immunology, Karolinska Institute, Stockholm, Sweden.
Nihlmark
E L
EL
Wigzell
H
H
Hansson
M
M
D000818:Animals; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D002454:Cell Differentiation; D002469:Cell Separation; D003208:Concanavalin A; D003601:Cytotoxicity Tests, Immunologic; D005434:Flow Cytometry; D007376:Interleukin-2 / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D015375:Receptors, Interleukin-2 / Q000276:immunology; D013154:Spleen / Q000166:cytology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology
D015704:CD4 Antigens; D016827:CD8 Antigens; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D003208:Concanavalin A