SERUM CYTOKINES IN PATIENTS WITH LEGIONELLA-PNEUMONIA - RELATIVE PREDOMINANCE OF TH1-TYPE CYTOKINES

Serum samples from 14 patients with Legionella pneumonia were examined for the presence of cytokines. In spite of high levels of serum C-rea ctive protein in all patients during the acute phase in only four case s (one involving interleukin-1 beta [IL-1 beta], 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 d etected in only one patient each. In contrast, significant increases o f serum gamma interferon (IFN-gamma) and IL-12 levels were observed du ring the acute phase in 6 and 11 cases, respectively. Interestingly, a lthough serum IFN-gamma levels diminished thereafter, in seven cases I L-12 levels remained high or increased further during the convalescent phase. In an additional 22 cases clinically suspected to be but not d iagnosed as Legionella pneumonia, increases of serum IL-12 levels were observed in 16 cases, whereas the remaining 6 cases showed no detecta ble IL-12. Our results demonstrate the relative predominance of Th1 cy tokine production in Legionella pneumonia. Although the role and signi ficance of prolonged increases in IL-12 levels in Legionella disease a re unknown, our results should prompt further investigation of the hos t immune response in terms of Th1 and Th2 balance in legionellosis.