Serum cytokines in patients with Legionella pneumonia: relative predominance of Th1-type cytokines

Clin Diagn Lab Immunol. 1998 May;5(3):401-3. doi: 10.1128/CDLI.5.3.401-403.1998.


Serum samples from 14 patients with Legionella pneumonia were examined for the presence of cytokines. In spite of high levels of serum C-reactive protein in all patients during the acute phase in only four cases (one involving interleukin-1beta [IL-1beta], three involving IL-6, and none involving tumor necrosis factor alpha) was the concentration of cytokines more than 100 pg/ml. Th2 cytokines IL-4 and IL-10 were detected in only one patient each. In contrast, significant increases of serum gamma interferon (IFN-gamma) and IL-12 levels were observed during the acute phase in 6 and 11 cases, respectively. Interestingly, although serum IFN-gamma levels diminished thereafter, in seven cases IL-12 levels remained high or increased further during the convalescent phase. In an additional 22 cases clinically suspected to be but not diagnosed as Legionella pneumonia, increases of serum IL-12 levels were observed in 16 cases, whereas the remaining 6 cases showed no detectable IL-12. Our results demonstrate the relative predominance of Th1 cytokine production in Legionella pneumonia. Although the role and significance of prolonged increases in IL-12 levels in Legionella disease are unknown, our results should prompt further investigation of the host immune response in terms of Th1 and Th2 balance in legionellosis.

MeSH terms

  • Cytokines / blood*
  • Humans
  • Interferon-gamma / blood
  • Interleukin-12 / blood
  • Legionella / isolation & purification
  • Legionella pneumophila / isolation & purification
  • Legionellosis / diagnosis
  • Legionellosis / immunology*
  • Legionnaires' Disease / immunology*
  • Pneumonia, Bacterial / diagnosis
  • Pneumonia, Bacterial / immunology*
  • Th1 Cells / immunology*


  • Cytokines
  • Interleukin-12
  • Interferon-gamma