QUANTIFICATION OF HUMAN INTERLEUKIN 18 mRNA EXPRESSION BY COMPETITIVE REVERSE TRANSCRIPTASE POLYMERASE CHAIN REACTION

• Published in: Cytokine (Philadelphia, Pa.) Vol. 11; no. 6; pp. 451 - 458
• Main Authors: Klein, Stefan A., Ottmann, Oliver G., Ballas, Karin, Dobmeyer, Thomas S., Pape, Martine, Weidmann, Eckhart, Hoelzer, Dieter, Kalina, Uwe
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.1999
• Subjects: Binding, Competitive; competitive reverse transcriptase/IGIF/interleukin 18/polymerase chain reaction; Humans; Interleukin-18 - genetics; Leukocytes, Mononuclear - metabolism; Linear Models; Reproducibility of Results; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - biosynthesis; Sensitivity and Specificity; Templates, Genetic; competitive reverse transcriptase/IGIF/interleukin 18/polymerase chain reaction
• ISSN: 1043-4666; 1096-0023
• DOI: 10.1006/cyto.1998.0424

Interleukin 18 (IL-18) is a recently identified cytokine, originally called interferon γinducing factor, due to its capacity to induce interferonγ production in Th1 type cells. IL-18 is expressed by a wide variety of cell types including mononuclear phagocytes, osteoblasts, keratinocytes and adrenal cortex cells. To quantify human IL-18 mRNA expression in small-scale cell samples the authors developed a competitive reverse transcriptase polymerase chain reaction using a competitive template as an internal standard. This assay was demonstrated as a valid, sensitive and precise tool to quantify human IL-18 mRNA expression. IL-18 mRNA expression of primary peripheral blood monocytes, CD4+T cells, CD8+T cells, B cells and NK cells was assessed by competitive RT-PCR. Basal IL-18 expression could be detected in all types of peripheral blood mononuclear cells (PBMC). The kinetics of IL-18 mRNA expression in PBMC from healthy donors was defined in vitro after monocyte-specific (lipopolysaccharide LPS), T-cell-specific (anti-CD3) and polyclonal-unspecific stimulation (phytohaemagglutinin PHA). Only LPS led to a strong increase of IL-18 mRNA expression peaking after 2h. These results indicate that IL-18 is expressed constitutionally by all major PBMC subtypes. However, only monocyte specific stimulation resulted in a significant induction of IL-18 mRNA expression suggesting activated monocytes e.g. in inflammation as the main source of IL-18 expression.