title: Radiation pneumonitis: a possible lymphocyte-mediated hypersensitivity reaction.
abstract: OBJECTIVE
  To determine if unilateral thoracic irradiation results in a lymphoid alveolitis in both irradiated and unirradiated lung fields.
  
  
  METHODS
  A prospective, nonrandomized study.
  
  
  METHODS
  Women receiving postoperative radiotherapy for carcinoma of the breast were evaluated both before and 4 to 6 weeks after radiotherapy. Findings after radiotherapy in 15 asymptomatic patients were compared with findings in a group of patients with clinical radiation pneumonitis.
  
  
  METHODS
  History, physical examination, chest radiograph, quantitative gallium lung scanning, respiratory function tests, bronchoalveolar lavage, and lavage lymphocyte subset analysis.
  
  
  RESULTS
  After irradiation, lavage lymphocytes increased significantly (34.5% versus 46.8%; P = 0.01) in the 17 patients studied prospectively. There was an associated reduction in vital capacity (102.5% versus 95.5%; P = 0.04). Comparison of results in patients before treatment, after treatment without clinical pneumonitis, and after treatment with clinical pneumonitis showed a dramatic increase in total lymphocytes after irradiation (6.3 versus 9.4 versus 35.2 million, respectively; P = 0.005), particularly in those with clinical pneumonitis. Only in those with clinical pneumonitis was this accompanied by an increase in the gallium index (3.7 versus 3.4 versus 9.0, respectively; P < 0.001). Vital capacity was also progressively reduced (102.5% versus 96.9% versus 76.7%, respectively; P = 0.04), as was diffusing capacity (98.6% versus 91.4% versus 72.6%, respectively; P = 0.003). No statistical differences existed between irradiated and unirradiated sides of the chest in either lavage or gallium lung scan studies.
  
  
  CONCLUSIONS
  In most patients, a lymphocytic alveolitis develops in both lung fields after strictly unilateral thoracic irradiation; this is more pronounced in patients developing clinical pneumonitis. These findings suggest that radiotherapy may cause a generalized lymphocyte-mediated hypersensitivity reaction.
authors: St. Vincent's Hospital, University of New South Wales, Australia.
authors: C M
authors: CM
authors: Roberts
authors: E
authors: E
authors: Foulcher
authors: J J
authors: JJ
authors: Zaunders
authors: D H
authors: DH
authors: Bryant
authors: J
authors: J
authors: Freund
authors: D
authors: D
authors: Cairns
authors: R
authors: R
authors: Penny
authors: G W
authors: GW
authors: Morgan
authors: S N
authors: SN
authors: Breit
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000532:radiotherapy; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D008214:Lymphocytes / Q000502:physiology*; D008875:Middle Aged; D011446:Prospective Studies; D011658:Pulmonary Fibrosis / Q000209:etiology* / Q000276:immunology; D011832:Radiation Injuries / Q000276:immunology*; D011878:Radiotherapy / Q000009:adverse effects; D012130:Respiratory Hypersensitivity / Q000209:etiology*; D016176:T-Lymphocyte Subsets