SFTPD and idiopathic pulmonary fibrosis: Although Krebs von den Lungen-6 (KL-6) and surfactant protein D (SP-D) are used clinically in Japan as prognostic markers for IPF (Yokoyama et al. 2006; Takahashi et al. 2000), few studies have investigated the relationship between these and sICAM-1 in patients with IPF.