A case of Sairei-to-induced pneumonitis diagnosed by lymphocyte stimulation test of bronchoalveolar lavage fluid

A 51-year-old woman was admitted with fever, cough and dyspnea. She had been taking Sairei-to, a traditional Chinese medicine, for 2 months. On admission, chest X-ray revealed a ground-glass appearance in the lung fields bilaterally and serum LDH was elevated. A differential cell count of the bronchoalveolar lavage fluid (BALF) showed that lymphocytes were increased, with a decreased ratio of CD4/CD8 cells. A lymphocyte stimulation test (LST) for Sairei-to using the lymphocytes in BALF was a positive, although a test of peripheral blood was negative. Sairei-to-induced pneumonitis was diagnosed based on the clinical course, laboratory findings, BALF cell analysis and LST of BALF. Only 4 cases of pneumonitis due to Sairei-to have been reported. This case suggests that LST of BALF is useful for diagnosing drug-induced pneumonitis.