Methotrexate treatment of a number of diseases is of established benefit, but adverse pulmonary reactions to the drug are also well known. Pneumonitis caused by methotrexate was first clearly described in 1969. This form of pulmonary disease has been related to the drug and not to the underlying disease because no other cause was found and pulmonary abnormalities regressed after cessation of methotrexate therapy. In some patients pulmonary biopsies have been performed. We report herein three cases of methotrexate-induced pneumonitis which suggest that cell-mediated immunity may play a role in its pathogenesis.
Material and Methods
Three nonsmoking women 42, 18, and 62 years of age, with respectively, choriocarcinoma, acute myelogenous leukemia, and breast cancer, where given methotrexate weekly (mean dose: 24 mg; range: 15-30) over a period averaging 42 days (range: 35-49). The exact weekly dosing schedules and duration of treatment were respectively 30 mg and five weeks for patient 1,15 mg and six weeks for patient 2, and 25 mg and seven weeks for patient 3. Injections were made, respectively, intramuscularly, intrathecally, and intravenously. A few days after the last injection, they complained of fever and dyspnea at effort. Chest x-ray films showed extensive alveolar and/or interstitial opacities in both lungs; hypoxia was present (mean level: 50 mm Hg, ie, 6.65 kPa). Bronchoalveolar lavage showed lymphocytic alveolitis (mean lymphocyte percentage: 61 percent) with, in two cases, an OKT4:OKT8 lymphocyte ratio of 0.50 and 0.43 (normal: 1.8±0.7). Recovery occurred (on the 14th, 10th, and 18th days, respectively) (mean delay: 14 days) when methotrexate treatment was stopped.
Leukocyte Migration Inhibition Test in Presence of Methotrexate
Heparinized (20 U/ml) peripheral blood was used for the leukocyte migration inhibition (LMI) test. This test was performed respectively on the 8th, 15th, and 8th days after the onset of the pneumonitis. Leukocytes of each patient were isolated by centrifugation on Percoll gradients. After washing and counting, granulocytes of each subject were mixed with her own lymphocytes in a ratio of 2:1 respectively; in case 2, one half of the granulocytes were mixed with lymphocytes from a healthy control subject, and the other half with the patients own lymphocytes. Agarose microdroplets containing mixed cell suspension were placed in wells of sterile disposable polystyrene plates. Cells were cultured in RDMI 1640 medium containing 20 mM HEPES buffer, 100 U/ml penicillin, 100 μg/ml streptomycin, and 20 percent fetal calf serum, hereafter called cell culture medium. The main idea of web sites is to inform people about this or that disorder. The main idea of web sites is to inform people about this or that disorder. Visit to Canadian Health Care – news online – read the information on this web site and you will understand properly that this is the main aim set.
We used cell culture medium without methotrexate and cell culture medium with different concentrations of the drug (10 logs; from 10~ through 103 μg/ml): these in vitro methotrexate concentrations are close to therapeutic plasma levels of methotrexate usually registered. Leukocyte migration from 12 agarose microdroplets was quantitated for each methotrexate concentration with a photoelectric procedure previously described. No other causes of pulmonary disease of acute onset were found: clinical and laboratory investigations for a bacterial, viral, fungal, parasitic, or malignant process were negative. Cell migration in medium with methotrexate was compared with migration of the same cells in medium without the drug; inhibition of leukocyte migration (LMI) was calculated in percentage by comparison with migration in medium without the drug; a curve was then obtained by plotting percent LMI against methotrexate concentration (log). Migration evaluation and calculations were done on 12, 24, 36, and 72 hour cultures; maximal inhibitions were observed by the 24th or the 36th hour. A LMI of more than 20 percent was considered significant. Variation in migration of control microdroplets was less than 10 percent; a variation of 2 percent of droplet size was due to the device used. This test was performed in our three patients. It was simultaneously performed in six normal subjects (“healthy controls”) and in three other patients with breast cancer and on methotrexate treatment but who were free from pneumonitis (“controls + methotrexate”).