Expression of the interleukin-2 receptor on human fibroblasts and its biological significance.
In this study, we have investigated the expression of the alpha and beta chains of the IL-2 receptor (IL-2R alpha, IL-2R beta) both at the membrane and at transcriptional levels during the lifespan of human embryonic fibroblasts. Here we show that the mAbs IOT14 and MIK beta 1 directed against the IL-2 binding sites of the IL-2R alpha and IL-2R beta respectively, stain human embryonic fibroblasts early in their life span. Data from [125I]rIL2 cross-linking experiments show the simultaneous expression of two IL-2 binding peptides of 70 and 55 kDa respectively on embryonic young fibroblasts as on lymphoid activated cells. The p55 and the p70 IL-2 binding peptides are shown to be specific for the IL-2R alpha and to the IL-2R beta by the finding that these bands are abolished by excess amounts of cold IL-2 and mAbs directed against the IL-2 binding sites of the alpha and beta chains. Scatchard analysis after [125I]IL-2 labelling shows the presence of both high affinity (150 sites with a Kd of 147 pM) and low affinity (1100 sites with a Kd of 4 nM) IL-2 binding sites. Northern blot and dot blot analysis show the presence of specific transcripts for the IL-2R alpha and IL-2R beta genes in early passaged fibroblasts. By contrast, in senescent cultures, only the IL-2R beta transcript were detected. Finally, IL-2 at low concentrations (36 pM) down modulates the level of the intercellular adhesion molecule ICAM-1 in young but not in senescent cultures.(ABSTRACT TRUNCATED AT 250 WORDS)
Plaisance
S
S
U268 INSERM, Hôpital Paul Brousse, Villejuif, France.
Rubinstein
E
E
Alileche
A
A
Sahraoui
Y
Y
Krief
P
P
Augery-Bourget
Y
Y
Jasmin
C
C
Suarez
H
H
Azzarone
B
B
D015815:Cell Adhesion Molecules / Q000378:metabolism; D002460:Cell Line; D015536:Down-Regulation; D005347:Fibroblasts / Q000276:immunology*; D015870:Gene Expression; D006801:Humans; D018799:Intercellular Adhesion Molecule-1; D007700:Kinetics; D012313:RNA / Q000235:genetics / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000235:genetics / Q000378:metabolism*
D015815:Cell Adhesion Molecules; D015375:Receptors, Interleukin-2; D018799:Intercellular Adhesion Molecule-1; D012313:RNA