Radiation pneumonitis: A possible lymphocyte-mediated hypersensitivity reaction

C. M. Roberts, E. Foulcher, J. J. Zaunders, D. H. Bryant, J. Freund, D. Cairns, R. Penny, G. W. Morgan, S. N. Breit*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    185 Citations (Scopus)


    Objective: To determine if unilateral thoracic irradiation results in a lymphoid alveolitis in both irradiated and unirradiated lung fields. Design: A prospective, nonrandomized study. Patients: 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. Measurements: 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. Conclusion: 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.

    Original languageEnglish
    Pages (from-to)696-700
    Number of pages5
    JournalAnnals of Internal Medicine
    Issue number9
    Publication statusPublished - 1993


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