Defective expression of high affinity IL-2 receptors on activated T cells from aged humans.

Overview

The proliferative response of T cells from aged humans to a number of mitogens is significantly reduced. We report here that there is a decrease in high affinity IL-2 receptor (IL-2R) expression on activated T cells from aged humans. Scatchard analysis of the binding of [125I]IL-2 demonstrates fewer high affinity IL-2 binding sites. Autoradiographic techniques demonstrate that this results from there being fewer activated T cells from old as compared to young donors that express high affinity IL-2R. However, T cells from old donors that do not express high affinity IL-2 binding sites express both the IL-2 binding 55 and 75 kd chains. Thus, although the two IL-2 binding peptides are expressed on activated T cells from old donors, expression of the high affinity IL-2R is reduced. This may explain the decreased ability of T cells from old donors to respond to IL-2. The impaired ability of activated T cells from old donors to express high affinity IL-2R while expressing the 55 and 75 kd chains may provide insights into the mechanisms of IL-2 interactions with its receptor.