Serum KL-6 for the evaluation of active pneumonitis in pulmonary sarcoidosis

KL-6, a mucinous high-molecular weight glycoprotein, expressed on type II pneumonocytes, is elevated in the serum of patients with active interstitial pneumonia, Forty-seven patients with histologically confirmed sarcoidosis were analyzed by chest radiography, CT, Ga-67 scintigraphy, BAL fluid (BALF), and serum KL-6. Serum KL-6 level was significantly elevated in radiographic type II (945+/-725 U/mL; n=13; p<0.01) and type III (1,179+/-1,320 U/mL; n=9; p<0.01), as compared with type 0 (333+/-173 U/mL; n=10) and type I (430+/-225 U/mL; n=15), Serum KL-6 level was significantly elevated in patients with CT findings of irregular small opacities, ground-glass opacities, and thickened bronchovascular bundle (p<0.01), as compared to those without these findings, Serum KL-6 level was significantly elevated in patients with positive pulmonary accumulation in Ga-67 scintigraphy (1,108+/-1,014; n=20; p<0.001) as compared to those without accumulation (390+/-206; n=27), Serum KL-6 level was elevated in patients with a higher CD4(+)/CD8(+) ratio (greater than or equal to 3) in BALF, as compared to those with lower ratios, These results suggest that serum ICL-B is a useful marker of sarcoidosis activity.