Nakajima M, Toshiaki M, Yoshida K, Niki Y, Matsushima T
Department of Medicine, Kawasaki Medical School, Kurashiki, Japan.
Nihon Kokyuki Gakkai Zasshi. 1998 Sep;36(9):763-70.
A high level of serum KL-6 is a known feature of active pulmonary fibrosis. Some researchers have suggested that KL-6 is produced and secreted by type II pneumocytes. The present study evaluated serum KL-6 levels in patients with summer-type hypersensitivity pneumonitis (summer-type HP) (n = 6, 7 episodes), Mycoplasma pneumoniae pneumonia (n = 16), Chlamydia psittaci pneumonia (n = 3), Chlamydia pneumoniae pneumonia (n = 9), and bacterial pneumonia (n = 12). In addition, transbronchial lung biopsy (TBLB) specimens were examined pathologically in order to identify the site of production and secretion of KL-6. In patients with summer-type HP, the serum KL-6 levels exceeded 500 U/ml (2.996 +/- 2.016 U/ml), but was below 500 U/ml (302 +/- 126 U/ml, p < 0.001) in the patients with other infectious pneumonias, with the exception of two. One of these two patients with a high serum KL-6 level had adult respiratory distress syndrome due to Mycoplasma pneumoniae. The other had organizing pneumonia due to Chlamydia pneumoniae. TBLB specimens showed proliferative type II pneumocytes in all summer-type HP cases. We believe that the high serum KL-6 levels were produced by type II pneumocytes, and may provide a useful indicating serum marker for HP. Although serum LDH, serum CRP and PaO2 are known as monitoring markers in summer-type HP, our findings demonstrated no manifest correlations among these markers. However, serum KL-6 levels showed a strong positive correlation with serum LDH levels and an inverse correlation with serum CRP levels. These results suggest that serum KL-6 may be a better marker of the degree of disease activity than serum LDH, CRP, or PaO2 in summer-type HP.
血清KL-6水平升高是活动性肺纤维化的一个已知特征。一些研究人员认为，KL-6由II型肺细胞产生并分泌。本研究评估了夏季型过敏性肺炎（夏季型HP）患者（n = 6，7例发作）、肺炎支原体肺炎患者（n = 16）、鹦鹉热衣原体肺炎患者（n = 3）、肺炎衣原体肺炎患者（n = 9）和细菌性肺炎患者（n = 12）的血清KL-6水平。此外，为了确定KL-6的产生和分泌部位，对经支气管肺活检（TBLB）标本进行了病理检查。在夏季型HP患者中，血清KL-6水平超过500 U/ml（2.996±2.016 U/ml），但在其他感染性肺炎患者中，除两例外，均低于500 U/ml（302±126 U/ml，p<0.001）。这两名血清KL-6水平高的患者中，一名因肺炎支原体感染患有成人呼吸窘迫综合征。另一名因肺炎衣原体感染患有机化性肺炎。TBLB标本显示，所有夏季型HP病例均有II型肺细胞增生。我们认为，血清KL-6水平升高是由II型肺细胞产生的，可能为HP提供一种有用的血清指示标志物。虽然血清LDH、血清CRP和PaO2是夏季型HP的已知监测标志物，但我们的研究结果表明这些标志物之间没有明显相关性。然而，血清KL-6水平与血清LDH水平呈强正相关，与血清CRP水平呈负相关。这些结果表明，在夏季型HP中，血清KL-6可能比血清LDH、CRP或PaO2更能反映疾病活动程度。
