The interleukin-2 receptor in human monocytes and macrophages: regulation of expression and release of the alpha and beta chains (p55 and p75).
Human monocytes constitutively express the intermediate-affinity interleukin-2 receptor (IL2R) p75, while freshly isolated monocytes lack the low-affinity IL2R p55 (Tac antigen, CD25). Lipopolysaccharide (LPS) upregulates expression of p75 and effectively induces surface expression of CD25 on human monocytes within 18 h, as detected by two-colour FACS analysis on 59.5 +/- 7.6% of cells. IL2-binding studies using biotinylated IL2 reveal the presence of a functional high-affinity receptor on LPS-activated monocytes. Soluble CD25 (sCD25) is not released into supernatants of elutriation-purified monocytes cultured for 24 h with 100 ng/ml LPS. When these monocytes are cultured for up to 7 days in the presence of serum to induce differentiation into macrophages, increasing amounts of sCD25 can be measured in the 24-h supernatants induced with LPS (173 +/- 86 U/ml at day 7), whereas the percentage of CD25+ cells (14.8 +/- 14.1% at day 7) is significantly lower than in monocytes. Thus, the cell surface expression and release of CD25 is differentially regulated in activated monocytes and macrophages.
Scheibenbogen
C
C
The University, Dept. of Hematology and Oncology, Heidelberg, Germany.
Keilholz
U
U
Richter
M
M
Andreesen
R
R
Hunstein
W
W
D006801:Humans; D066298:In Vitro Techniques; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology*; D008970:Molecular Weight; D009000:Monocytes / Q000276:immunology*; D011487:Protein Conformation; D015375:Receptors, Interleukin-2 / Q000737:chemistry / Q000378:metabolism*
D015375:Receptors, Interleukin-2