title: Rheumatoid arthritis, methotrexate therapy, and Pneumocystis pneumonia.
authors.forename: R L
authors.initials: RL
authors.lastname: Leff
authors.forename: J P
authors.initials: JP
authors.lastname: Case
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008727:Methotrexate / Q000009:adverse effects* / Q000627:therapeutic use; D011020:Pneumonia, Pneumocystis / Q000209:etiology*
chemical_list: D008727:Methotrexate