肺癌患者に合併する感染症の病態・予後の解析 : 予後に関わる低アルブミン血症の臨床的意義

Abstract

The present study was conducted to determine what clinical factors affect the prognosis of lung cancer patients with infectious diseases. Among respiratory infections, bacterial pneumomnia was closely related to poor prognosis in lung cancer patients. Bacterial culture of transtracheal aspirates showed that Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis were most frequently isolated. Bacteria comprising normal flora in the upper tract and the oral cavity, such as a Streptococcus sp., were also isolated from transtracheal aspirates of lung cancer patients, which indicated a decrease in local resistance of the lower respiratory tract of such patlents. The onset of sepsis in lung cancer patients usually followed respiratory infection as a secondary complication; the major causative bacteria were Staphylococcus aureus and Esherchia coli. Lung cancer patients with hypoalbuminemia (serum albumin < 3.0g/dl) contracted respiratory infection and sepsis more frequently than did those with normoalbuminemia. Analysis of cytokine mRNA expression in peripheral blood mononuclear cells (PBMC) by reverse-transcriptase assisted polymerase chain reaction (RT-PCR) demonstrated that the expression of mRNA for interleukin (IL)-1β, IL-2, IL-8, interferon-γ, tumor necrosis factor-α and mannose binding protein was decireased in PBMC of lung cancer patients with hypoalbuminemia ; even the in vitro stimulation of PBMC with phytohemagglutin did not enhance the ability of PBMC to express mRNAs for those proteins. These results suggest that infectious diseases including respiratory infection and sepsis are a critical factor for the prognosis of lung cancer patients with hypoalbuminemia which affects the ability of PBMC to express mRNA for immunoregulatory proteins.