KL-6 as a Serologic Indicator of Pneumocystis carinii Pneumonia in Immunocompromised Hosts

KL-6, a serum marker for interstitial pneumonitis, was evaluated in patients with Pneumocystis carinii pneumonia (PCP). Patient 1 was a 56-year-old woman with rheumatoid arthritis treated with immunosuppressive drugs and corticosteroids. Patient 2 was a 59-year-old man with a glioblastoma who received anti-cancer drugs and corticosteroids. In both patients, serum KL-6 showed an abnormally high level due to the complication of PCP, and it decreased following successful treatment. These results indicate that PCP is one of the diseases in which serum KL-6 increases.