Objective: To explore the roles of immunological memory in the pathogenesis of myasthenia gravis (MG) by Bacillus Calmette-Guérin (BCG).
Methods: For this randomized comparative clinical trial, 58 newly diagnosed MG patients and 32 age-and-gender-matched healthy controls were analyzed by purified protein derivative (PPD) test. The results were observed after 72 hours. peripheral blood mononuclear cell (PBMC) was collected from the MG patients before and after extended thymectomy and cultured with BCG. After a 72-hour incubation, the level of interferon gamma (IFN-γ) was detected by enzyme-linked immunosorbent assay (ELISA).
Results: In PPD test, the MG patients did not show a markedly higher positive percentage [48.3% (28/58) vs 65.6% (21/32), P = 0.114]. The pre-thymectomy PBMC had a higher level of IFN-γ than the control group: (650 ± 312) pg/ml vs (346 ± 153) pg/ml. After extended thymectomy, the level of IFN-γ returned to normal: (219 ± 113) pg/ml. The P value is 0.003, 0.001.
Conclusion: The impairment of immunological memory, may be an important pathogenic cause of relapse in the MG patients.