title: The relation between serum cytokine levels and common laboratory tests in healthy Japanese males.
abstract: OBJECTIVE
  Cytokines are critical regulatory molecules that circulate in blood at measurable levels. However, the epidemiology of serum cytokine levels in healthy populations is still limited, particularly for Japanese populations. The objective of this study was to examine the relation between serum cytokine levels and common laboratory tests in a healthy Japanese population.
  
  
  METHODS
  We studied serum levels of six cytokines (interleukin-4 (IL-4), IL-5, IL-6, IL-10, interferon-γ (IFN-γ), granulocyte-macrophage colony-stimulating factor (GM-CSF)) in a healthy Japanese population using a sensitive chemiluminescence ELISA (CL-ELISA). We examined the relations between serum cytokine levels and common laboratory tests using multiple regression analysis. We were particularly interested in potential relations between serum cytokine levels and C-reactive protein (CRP) in light of its relation to the risk of cardiovascular events. We also investigated the relation between cytokine levels, alcohol consumption and smoking.
  
  
  RESULTS
  After adjusting for the influence of other cytokines and laboratory tests, the serum level of IL-4 was associated with IL-5 and GM-CSF. In addition to IL-4, IL-5 was also associated with IL-10 and IFN-γ. IL-6 was associated with IL-10 and IFN-γ, and IL-10 and IFN-γ were associated with GM-CSF. CRP was significantly negatively associated with serum IL-4 level. IL-6 was weakly correlated with alcohol consumption level in this population. IL-5 among smokers tended to be lower than that among nonsmokers.
  
  
  CONCLUSIONS
  Close relations among serum cytokine levels were observed in a healthy population. It is interesting that the level of IL-4, an anti-inflammatory cytokine, was inversely related to CRP level, suggested to be a marker of inflammation.
authors: Department of Public Health School of Medicine, Fukushima Medical University, Hikarigaoka I, 960-1295, Fukushima, Fukushima, Japan, mtsunoda@fmu.ac.jp.
authors: Masashi
authors: M
authors: Tsunoda
authors: Humio
authors: H
authors: Tsunoda
authors: Lucille
authors: L
authors: Guevarra
authors: David J
authors: DJ
authors: Tollerud