Effect of Selenium on the Expression and Function of the Interleukin-2 Receptor
This study examined the effect of dietary (2ppm for 8 weeks) or in vitro (1 × 10−7M) supplementation with Se (as sodium selenite) on the expression of the p55 and p75 subunits of the interleukin-2 receptor (I12R) and the function of p55/p75 on the surface of lymphoblasts from 12 week-old C57B1/6J male mice. Scatchard analyses of 125I-I12 binding (2nM-6pM) on the surface of Con A induced (5μg/ml; 48h) pooled spleen lymphoblasts indicated that cells from Se-supplemented animals expressed significantly higher numbers per cell of low (53,687 ± 6160; Kd 3.31 × 10−9M) and high affinity (3,235 ± 216; Kd = 6.91 × 10−11M) I12R as compared to cells from Se-normal animals (34,648 ± 2923, Kd = 1.78 × 10−9; 2,169 ± 95, Kd = 4.36 × 1011M, respectively). The numbers of both p55 (56,908 ± 5980) and p75 (12,736 ± 839) expressed per cell were also significantly higher than on cells from Se-normal animals (37,203 ± 2988; 9663 ± 1009, respectively), but their ratios were comparable. Supplementation with Se in vitro resulted in similar changes. The high affinity receptors on both cell types internalized I12 at the same rate (15 ± 0.9 and 14 ± 1.2 min 50% I12 internalization) but a significantly higher number of 125I-I12 molecules were internalized by cells from Se-supplemented animals (1305 ± 107 vs. 835 ± 96) at 60 min after exposure. The results indicated that Se regulates the expression of both subunits of the I12R and thus can modulate I12-dependent responses.