Interferons α / β inhibit IL‐7‐induced proliferation of CD4 − CD8 − CD3 − CD44 + CD25 + thymocytes, but do not inhibit that of CD4 − CD8 − CD3 − CD44 − CD25 − thymocytes

Open Access
Publisher Website
Google Scholar
Abstract
Type 1 interferons (IFN‐α/β) have recently been shown to inhibit interleukin‐7 (IL‐7)‐induced growth and survival of early B‐lineage cells. The CD3− CD4− CD8− (triple negative; TN) thymocytes from normal mice strongly proliferated upon stimulation with IL‐7 in suspension culture. Such an IL‐7‐induced proliferation was suppressed by the addition of IFN‐α/β, but a fraction of the TN thymocytes still showed proliferation. The IL‐7‐induced growth of TN thymocytes from scid mice, which lack the CD44− CD25− subpopulation, was completely inhibited by the addition of IFN‐α/β. The IL‐7 induced proliferation of CD4− CD8− thymocytes from T‐cell receptor (TCR) transgenic mice, the majority of which are CD3+ CD44− CD25−, was resistant to IFN‐α/β‐mediated suppression. In fetal thymus organ cultures (FTOC), the addition of IL‐7 greatly increased the population of CD4− CD8− CD44+ CD25+ thymocytes and IFN‐α/β inhibited this IL‐7‐driven expansion. In contrast, the addition of IL‐7 markedly decreased the percentages of CD4− CD8− CD3− CD44− CD25− cells, and IFN‐α/β reversed the effect and increased the subpopulations of CD44− CD25+ and CD44− CD25.− Finally, IFN‐β mRNA was found to be expressed in the thymus. The data suggest that type 1 interferons inhibit IL‐7‐driven proliferation of TN thymocytes, but do not block the normal differentiation process.