Interleukins (IL)‐1 and IL‐2 control IL‐2 receptor α and β expression in immature thymocytes

Abstract

Functional high-affinity interleukin-2 receptors (IL-2R) contain three transmembrane proteins, IL-2R alpha, beta and gamma. We have investigated the expression of IL-2R alpha and beta genes in immature mouse thymocytes. Previous work has shown that during differentiation these cells transiently express IL-2R alpha on their surface. Stimulation of IL-2R alpha+ and IL-2R alpha- immature thymocytes with phorbol 12-myristate 13-acetate and calcium ionophore induces synthesis of IL-2R alpha and IL-2R beta mRNA. Most of this response depends on autocrine stimulation by IL-2. IL-1 synergizes with IL-2 to induce a 120-fold increase in IL-2R alpha mRNA and a 14-fold increase in IL-2R beta mRNA levels. A large proportion of the stimulated cells contains both transcripts. These interleukins do not induce any differentiation to more mature phenotypes. Collectively, these results show that IL-2 plays a major role in the regulation of IL-2R expression in normal immature thymocyte. We suggest that this response to interleukins may be part of a homeostatic mechanism to increase the production of immature thymocytes during stress.

Embryonic age influences the capacity for cytokine induction in chicken thymocytes

“…The short duration of the response to mitogen in thymocytes at E14 suggests initial activation of the protein kinase C signalling cascade, with either inhibition of the response by 12–18 hr, or failure of a second signal required for sustained proliferation beyond 12 hr. The down‐regulation of IL‐2, by an as yet unknown mechanism, in all embryonic thymocyte subsets is consistent with the absence of an autocrine signal, believed to be required for sustained activation and proliferation in mature thymocytes 16 …”

“…The down-regulation of IL-2, by an as yet unknown mechanism, in all embryonic thymocyte subsets is consistent with the absence of an autocrine signal, believed to be required for sustained activation and proliferation in mature thymocytes. 16 By using highly sensitive real-time quantitative RT-PCR assays constitutive expression of transcripts was measured. Constitutive expression of transcripts was demonstrated for all cytokines tested in unsorted thymocytes at all developmental stages (with the exception of IFN-g in D1 thymocytes), and in most thymic subsets at E18 (Fig.…”

The IL‐2/IL‐2‐Receptor Complex in the Maturation of Rat T‐Cell Progenitors

“…Our results obtained after IL-2 and anti-CD25 treatments, in agreement with previous findings in both humans and mice (Toribio et al, 1988;ZufiigaPflticker and Kruisbeek, 1990;Wilson et al, 1994) also indicate that IL-2 promotes the differentiation of thymic-cell precursors, as a consequence of its capacity to stimulate cell proliferation.…”

Immunocytochemical Evidence for Interleukin-2 Receptor Regulation on Rat Anterior Pituitary and Adrenal Cells.

“…In fact in a preliminary experiment, the IL-2R staining of Tlymphoblasts was more intense even with the use of higher Ab dilutions than used for these cultured endocrine cells (data not shown) . IL-2-induced increase in ATR-18 immunostaining observed in this study is almost comparable with that reported about the lymphocytes [10,14,23,30]. It is of value to be indicated that IL-2 used in this study was at the half-maximum effective concentration which induced corticosterone biosynthesis in our previous adrenal cell culture study [12].…”