Mycobacterium tuberculosis DNA in tissue affected by sarcoidosis

OBJECTIVE

To investigate the prevalence of Mycobacterium tuberculosis DNA in granulomatous tissues from patients with sarcoidosis and from controls matched for age, sex, and tissue by using the polymerase chain reaction.

DESIGN

Single blind control trial.

SUBJECTS

16 patients with sarcoidosis who had undergone diagnostic biopsy of lung, skin, or lymph node and 16 patients with squamous cell carcinoma or Hodgkin's disease to act as controls. In addition, four lung specimens infected with M tuberculosis were included as positive controls.

RESULTS

M tuberculosis DNA was present in sarcoid tissues containing granulomas from seven of the 16 patients and one of the 16 matched controls. Two of the four specimens known to be infected with M tuberculosis were positive in the controlled experiment.

CONCLUSION

These figures suggest that M tuberculosis DNA is detected as readily in patients with sarcoidosis as in patients with frankly tuberculous tissues and imply that M tuberculosis may be linked to the cause of sarcoidosis.

Sarcoidosis

Sarcoidosis is a multisystem disorder of unknown cause characterized by non-caseating granuloma formation and evidence of enhanced cellular immune response at the site of involvement. Although the majority of patients have a self-limiting illness, a significant proportion develop severe chronic disability.

Detection of mycobacterial DNA in sarcoidosis and tuberculosis with polymerase chain reaction

The cause of sarcoidosis is unknown. However, the histological similarity between the disorder and tuberculosis suggests that mycobacteria might contribute to the pathogenesis of sarcoidosis. We have used the polymerase chain reaction (PCR) to detect mycobacterial DNA in clinical samples from patients with sarcoidosis. 104 patients were included in the study (62 referred for possible tuberculosis and 20 for possible sarcoidosis, and 22 control patients who had undergone bronchoscopy for other reasons). Bronchoalveolar lavage samples, bronchial washings, and tissue specimens (1 from each patient) underwent assay by PCR as well as bacteriological, histological, and cytological examination. We used two PCR reactions: in the first the complex-specific insertion sequence IS986/IS6110 was used to specifically detect DNA from Mycobacterium tuberculosis complex bacteria; in the second, conserved sequences of the mycobacterial groEL gene were used to detect DNA from mycobacteria other than M tuberculosis. The PCR was more sensitive than culture for diagnosis of tuberculosis. However, the false-positive PCR rate for M tuberculosis was 9%. M tuberculosis DNA was found in half the sarcoidosis patients, and non-tuberculosis mycobacterial DNA in a further 20%. The findings that a significant proportion of the sarcoidosis patients in this study have mycobacteria in their lungs and that most of these mycobacteria belong to M tuberculosis complex suggest an aetiological role for mycobacteria in sarcoidosis.

Tumour necrosis factor production by alveolar macrophages in pulmonary sarcoidosis and tuberculosis

Tumour Necrosis Factor alpha (TNF/Cachectin) is a cytokine produced mainly by macrophages, which has been shown to cause endothelial cell damage, pyrexia and weight loss, clinical features of tuberculosis, but not of sarcoidosis which is in many other respects a similar disease. 1,25 di-hydroxy Vitamin D and gamma interferon, factors which are present in vivo in both tuberculosis and sarcoidosis, enhance the ability of macrophages to release TNF in vitro. We have studied the ability of pulmonary alveolar macrophages (PAM) harvested by broncho-alveolar lavage (BAL) to produce TNF in response to stimulation with E. coli endotoxin lipopolysaccharide (LPS). 25 patients undergoing bronchoscopy and BAL were studied: 9 with sarcoidosis, 7 with tuberculosis (TB) and 9 (non-neoplastic) disease controls. TNF was assayed by Enzyme Linked Immunosorbent Assay (ELISA) in lavage fluid and cell culture supernatants. No TNF was detected in lavage fluid from any of the groups. PAMs from control patients released no detectable TNF spontaneously, but released 59 +/- 31 units after LPS stimulation. Cells from patients with sarcoidosis and tuberculosis released TNF spontaneously in vitro (TB 226 +/- 106 units; Sarcoidosis 293 +/- 176). TNF release by these cells was not increased further by addition of an optimal concentration of LPS. Thus, the pulmonary macrophages of patients with sarcoidosis and tuberculosis released significantly more TNF than those of controls.

Isotretinoin and lung function in systemic sclerosis

During an open prospective study of the synthetic retinoid isotretinoin in ten patients with systemic sclerosis, one patient developed an eosinophilic pleural effusion and two patients were noticed to have asymptomatic deterioration in pulmonary function tests. The pulmonary function of all treated patients was then compared retrospectively with a similar control group of patients not treated with isotretinoin. There was a significantly greater decrease in the 1-s forced expiratory volume and transfer coefficient in the patients with systemic sclerosis being treated with isotretinoin in comparison to the untreated control patients. Studies of lung function in patients treated with isotretinoin for other indications are required.

Tumour necrosis factor in bronchopulmonary secretions of patients with adult respiratory distress syndrome

Tumour necrosis factor (TNF) concentrations were measured in the bronchopulmonary secretions of 5 patients with the adult respiratory distress syndrome. Each patient underwent fibreoptic bronchoscopy and bronchopulmonary aspiration, and control samples were obtained in an identical manner from 24 patients who underwent bronchoscopy for other reasons (8 had tuberculosis, 6 had sarcoidosis, and 10 had haemoptysis but no abnormal findings). Aspirated fluid was assayed for the presence of TNF by use of an enzyme-linked immunosorbent assay. In the 5 patients with adult respiratory distress syndrome, TNF concentrations exceeded 500 U/ml (12.5 ng/ml), whereas in the control samples no TNF was detected.

Bronchoalveolar lavage cell counts as a predictor of short term outcome in pulmonary sarcoidosis

Sixty seven patients with biopsy proven pulmonary sarcoidosis were prospectively studied to determine whether single point bronchoalveolar lavage cell counts were a useful indicator of functional outcome and whether repeated lavage helped in management. The mean follow up period was 25 (range 13-37) months. No patient was having corticosteroid treatment at the time of initial bronchoalveolar lavage. "High intensity alveolitis" (lymphocyte count greater than or equal to 28%) was present at the initial lavage in 42 patients. These patients showed a significant improvement in their pulmonary function and chest radiographs over the follow up period whereas patients with "low intensity alveolitis" did not. Of the 42 patients with high intensity alveolitis, 31 had chronic sarcoidosis (duration over two years, mean 80 months). These patients showed a significant improvement in FVC but not in TLCO. Corticosteroids resulted in greater functional and radiological improvement in the patients with high intensity alveolitis than in those with low intensity alveolitis. Repeat bronchoalveolar lavage in 34 patients, mean 8.4 months after the original lavage, showed a weak inverse relation between a reduced lymphocyte count and change in forced vital capacity and isotope uptake on a gallium scan. These correlations were too weak to make repeated cell counts useful in management. Our results suggest that high intensity alveolitis may be a favourable prognostic factor for lung function in pulmonary sarcoidosis, even in patients with chronic disease, but that repeat lavage adds little to the management of the individual patient.

Metastatic uterine leiomyosarcoma in association with recurrent lung abscess

A case of metastatic uterine leiomyosarcoma complicated by recurrent lung abscesses is described.