Expression and responsiveness of human interleukin-18 receptor (IL-18R) on hematopoietic cell lines.
Interleukin-18 (IL-18) is a new inflammatory cytokine sharing biological functions with IL-12. The human IL-18 receptor (IL-18R) was recently identified and was found to be expressed on normal peripheral blood lymphocytes. To further characterize IL-18R, we analyzed IL-18R expression using a series of human hematopoietic cell lines selected from various cell lineages. We found the IL-18R expression on cells of T and B lineages as expected from analysis on normal cells. The IL-18R expression, however, was found not to be restricted to any specific maturation stages of T and B cells. In addition, we detected IL-18R expression in myeloid, monocytoid, erythroid and megakaryocytic cell lines, indicating that normal counterparts of these cell lineages could express IL-18R and participate in in vivo reactions caused by IL-18. Biochemical studies showed that IL-18R proteins exist as heterogeneous molecules ranging from 60 to 110 kDa. Deglycosylation experiments indicated that the heterogeneity could not be explained only by a difference in glycosylation. We also found that tumor necrosis factor-alpha (TNF-alpha) modulated the IL-18R expression, which implies an important in vivo effect of TNF-alpha on IL-18-induced reaction. Analyzing the responsiveness of IL-18R, we found that only KG-1 responded to IL-18 stimulation. This suggests that certain inhibitory mechanisms of IL-18 responsive genes are involved in the all IL-18R-positive cell lines except KG-1.
Nakamura
S
S
Fujisaki Cell Center, Hayashibara Biochemical Laboratories, Inc., Okayama, Japan.
Otani
T
T
Okura
R
R
Ijiri
Y
Y
Motoda
R
R
Kurimoto
M
M
Orita
K
K
D001402:B-Lymphocytes / Q000276:immunology; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism*; D002461:Cell Line, Transformed; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006031:Glycosylation; D006801:Humans; D018664:Interleukin-12 / Q000494:pharmacology; D020382:Interleukin-18 / Q000378:metabolism; D053727:Interleukin-18 Receptor alpha Subunit; D018123:Receptors, Interleukin / Q000235:genetics* / Q000378:metabolism; D053724:Receptors, Interleukin-18; D013601:T-Lymphocytes / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation
C508572:IL18R1 protein, human; D020382:Interleukin-18; D053727:Interleukin-18 Receptor alpha Subunit; D018123:Receptors, Interleukin; D053724:Receptors, Interleukin-18; D014409:Tumor Necrosis Factor-alpha; D018664:Interleukin-12