Improvement of pneumonia and arthritis in Felty's syndrome by treatment with granulocyte-macrophage colony-stimulating factor (GM-CSF).

A 63-year old man with Felty's syndrome and pneumonia of unknown origin was treated with GM-CSF. Granulocyte counts increased and arthritis-related symptoms improved under GM-CSF. Pneumonia was treated effectively with antibiotics only during or after GM-CSF application. This suggests, that antibiotic-resistant infections can be treated effectively in patients with Felty's syndrome when granulocyte counts are raised by GM-CSF.