Abnormal development of intestinal intraepithelial lymphocytes and peripheral natural killer cells in mice lacking the IL-2 receptor beta chain

Abstract

The interleukin-2 receptor beta chain (IL-2R beta) is expressed on a variety of hematopoietic cell types, including natural killer (NK) cells and nonconventional T lymphocyte subsets such as intestinal intraepithelial lymphocytes (IEL). However, the importance of IL-2R beta-mediated signaling in the growth and development of these cells has yet to be clearly established. We have investigated IEL and NK cells in mice deficient for IL-2R beta and describe here striking defects in the development of these cells. IL-2R beta-/- mice exhibited an abnormal IEL cell population, characterized by a dramatic reduction in T cell receptor alpha beta CD8 alpha alpha and T cell receptor gamma delta lymphocytes. This selective decrease indicates that IEL can be classified into those whose development and/or differentiation is dependent on IL-2R beta function and those for which IL-2R beta-mediated signaling is not essential. NK cell development was also found to be disrupted in IL-2R beta-deficient mice, characterized by a reduction in NK1.1+CD3- cells in the peripheral circulation and an absence of NK cytotoxic activity in vitro. The dependence of NK cells and certain subclasses of IEL cells on IL-2R beta expression points to an essential role for signaling through this receptor, presumably by IL-2 and/or IL-15, in the development of lymphocyte-subsets of extrathymic origin.

Figure 1

Flow cytometric analysis of Thy-1, TCRαβ, and TCRγδ expression on IEL from heterozygous (IL-2Rβ^+/−) and homozygous (IL2Rβ^−/−) IL-2Rβ–deficient mice. IEL isolated from IL-2Rβ^+/− or IL2Rβ^−/− mice were stained with anti–Thy-1 mAb, and anti-TCRαβ or anti-TCRγδ mAb, and viable cells were analyzed by flow cytometry. Numbers represent the percentage of total cells found in each quadrant.

Figure 2

Flow cytometric analysis of CD8αβ expression on TCRαβ⁺ IEL from IL-2Rβ–deficient mice. IEL isolated from IL-2Rβ^+/− or IL2Rβ^−/− mice were stained with anti-CD4, anti-CD8α, and anti-CD8β mAb. Cells gated on TCRαβ⁺ cells were analyzed for their expression of CD8α and CD8β. Numbers represent the percentage of total cells found in each quadrant.

Figure 3

NK cell cytolytic activity and development in IL-2Rβ–deficient mice. Top panels show lysis of YAC-1 target cells by (A) spleen MNC from poly(I):(C )–treated animals or (B) spleen MNC incubated in vitro with IL-12. IL-2Rβ^+/− MNC are represented by closed symbols; IL-2Rβ^−/− MNC are represented by open symbols. Data are shown as mean ± SEM for (A) five IL-2Rβ^+/− and five IL-2Rβ/- mice and for (B) four IL-2Rβ^+/− and two IL-2Rβ^−/− mice, analyzed in two separate experiments. (C) Flow cytometric analysis of NK1.1 and CD3 expression on NK cells in IL-2Rβ–deficient mice. PB cells from IL-2Rβ^+/− and IL2Rβ^−/− mice were stained with anti-NK1.1 and anti-CD3, and 10,000 viable lymphocytes were gated. Numbers represent the percentage of NK1.1⁺ cells in the gated population for a representative individual from each group.