Regulation of interleukin 2 (IL2) receptor expression: IL 2 as an inducing signal for the expression of its own receptor on a murine T helper cell line

The interleukin 2 receptor (IL2R) expression of a terpolymer of L-Glu60, L-Ala30, L-Tyr10 (GAT)-specific T helper (Th) cell line, L14, was studied using two different rat monoclonal antibodies specific for the murine IL2R, 7D4 and 5A2-2. L14 T cells expressed IL2R transiently, but contrary to the general assumption that IL2R expression is maintained only by periodic antigen stimulation, we observed that IL2 itself was able to regulate the level of IL2R on L14 Th lymphocytes. In particular, it was found that L14 T cells, which had not been recently stimulated and which expressed a very low level of high affinity IL2R, could be induced to exhibit a high level of this receptor after exposure to recombinant IL2, in the absence of any specific signal. In contrast, the Th cell line 52.3 used as control could be induced to express high levels of IL2R only after exposure to GAT; nevertheless, IL2 seems to play a critical role in the in vitro survival of the resting state of 52.3 T cells.