The IL-2 receptor present on human embryonic fibroblasts is functional in the absence of P64/IL-2Rγ chain

In this study, we have investigated the IL-2Rγ gene expression in several human embryonic fibroblasts which express other components of the IL-2 receptor (IL-2R). Polymerase chain reaction did not allow us to detect IL-2Rγ transcripts in these cells but the functionality of the IL-2Rαβ was not affected. Indeed, in the human IL-2Rα⁺β⁺γ^- embryonic lung fibroblasts ICIG-7, IL-2 induced identical phenomena to those previously reported in lymphoid cells: rapid internalization of the IL-2Rαβ - IL-2 complex, specific phosphorylation of cellular proteins (56 and 38 kDa) and up-regulation of ICAM-1 expression. IL-2 induction of ICAM-1 was only observed in sparse cultures and for IL-2 concentrations over 180 pM. We have also observed, in these fibroblastic cells, the up-regulation of ICAM-2 expression by IL-2, both in sparse and dense cultures. These data show that p64/1L-2Rγ expression in human embryonic fibroblasts does not correlate with the ability of the IL-2R to deliver a biological signal.