Enhanced expression of interleukin-18 receptor alpha chain by CD4+ T cells in sarcoidosis.

Abstract

STUDY OBJECTIVES:

To investigate the expression of interleukin-18 receptor alpha chain (IL-18Ralpha) in BAL and peripheral blood (PB) T cells in patients with sarcoidosis compared with control subjects, to evaluate the relationship between the expression and clinical manifestations, and to clarify the mechanisms of altered expression.

SUBJECTS AND METHODS:

The study subjects consisted of 21 patients with sarcoidosis and 8 normal control subjects. The expression of IL-18Ralpha was examined by flow cytometry.

RESULTS:

The proportions of BAL CD4+ and PB CD4+ T cells expressing IL-18Ralpha were significantly increased in patients with sarcoidosis compared to control subjects. BAL CD4+ T cells expressed IL-18Ralpha in a higher proportion than did paired CD8+ T cells in patients with sarcoidosis but not in control subjects. Greater proportions of BAL CD4+ T cells and BAL CD8+ T cells than of their PB counterparts expressed IL-18Ralpha in both patients and control subjects. CD4+ T cells were more sensitive to the induction of IL-18Ralpha by cytokines in vitro, such as interleukin (IL)-2, IL-12, and tumor necrosis factor-alpha than were CD8+ T cells. Increased expression of IL-18Ralpha by BAL T cells commonly observed in patients and control subjects was associated with the expansion of CD45RO+ cells in BAL T cells. However, there were no significant correlations between the expression of IL-18Ralpha by any cell populations and BAL findings, serum angiotensin-converting enzyme activities, radiograph stages, or clinical courses.

CONCLUSION:

The overexpression of IL-18Ralpha predominantly by CD4+ T cells in sarcoidosis emphasizes crucial roles played by T-helper type 1 cells in the IL-18/IL-18Ralpha system in sarcoidosis.

• Authors: Yanqiu Zhou, Etsuro Yamaguchi, Yoshinobu Fukui, Satoshi Konno, Yukiko Maeda, Koji Kimata, Masaharu Nishimura
• Journal: Chest (Chest) Vol. 128 Issue 4 Pg. 2497-503 (Oct 2005) ISSN: 0012-3692 [Print] United States
• PMID: 16236915 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• IL18R1 protein, human
• Interleukin-18 Receptor alpha Subunit
• Receptors, Interleukin
• Receptors, Interleukin-18

Topics

• Bronchoalveolar Lavage Fluid (immunology)
• CD4 Lymphocyte Count
• CD4-Positive T-Lymphocytes (immunology)
• Cells, Cultured
• Flow Cytometry
• Humans
• Interleukin-18 Receptor alpha Subunit
• Receptors, Interleukin (metabolism)
• Receptors, Interleukin-18
• Reference Values
• Sarcoidosis (immunology)
• T-Lymphocytes, Helper-Inducer (immunology)