Serum KL-6, a novel mucin-like glycoprotein, as an indicator of interstitial pneumonitis following lobectomy.

Serum KL-6 has been shown to be a useful marker of active interstitial pneumonitis in patients who have not undergone lobectomy. Considering that KL-6 is produced mainly in the distal airway epithelium, the present study was conducted to determine whether resected lung volume influenced the postoperative KL-6 levels, and also to evaluate whether it is a useful parameter in patients who have undergone lobectomy. The serum KL-6 levels decreased by 36% 1 week after lobectomy, but returned to the preoperative levels by 2 months postoperatively. Although the KL-6 levels increased by 100% 3 to 4 months after lobectomy, the levels were significantly lower than those in interstitial pneumonitis (P < 0.05). The decrease in the KL-6 levels correlated with the number of resected lung segments, but not with the changes in white blood cell count, lactate dehydrogenase level, or C-reactive protein level. In comparison with the lobectomy patients, the serum KL-6 levels decreased by half in patients who had undergone partial resection (P < 0.05). The results of this study suggest that the serum KL-6 level may be a useful indicator of interstitial pneumonitis after lobectomy. Serum KL-6 levels are influenced by the volume of the resected lung, and probably also by the upregulation of KL-6 production.