Bronchoalveolar lavage in patients with the acquired immune deficiency syndrome (AIDS)

Evaluation of immune responses in HIV infected patients with pleural tuberculosis by the QuantiFERON TB-Gold interferon-gamma assay

Background

Diagnosis of tuberculous (TB) pleuritis is difficult and better diagnostic tools are needed. New blood based interferon-gamma (IFN-γ) tests are promising, but sensitivity could be low in HIV positive patients. The IFN-γ tests have not yet been validated for use in pleural fluid, a compartment with higher level of immune activation than in blood.

Methods

The QuantiFERON TB^®-Gold (QFT-TB) test was analysed in blood and pleural fluid from 34 patients presenting with clinically suspected pleural TB. Clinical data, HIV status and CD4 cell counts were recorded. Adenosine deaminase activity (ADA) analysis and TB culture were performed on pleural fluid.

Results

The patients were categorised as 'confirmed TB' (n = 12), 'probable TB' (n = 16) and 'non-TB' pleuritis (n = 6) based on TB culture results and clinical and biochemical criteria. The majority of the TB patients were HIV infected (82%). The QFT-TB in pleural fluid was positive in 27% and 56% of the 'confirmed TB' and 'probable TB' cases, respectively, whereas the corresponding sensitivities in blood were 58% and 83%. Indeterminate results in blood (25%) were caused by low phytohemagglutinin (PHA = positive control) IFN-γ responses, significantly lower in the TB patients as compared to the 'non-TB' cases (p = 0.02). Blood PHA responses correlated with CD4 cell count (r = 0.600, p = 0.028). In contrast, in pleural fluid indeterminate results (52%) were caused by high Nil (negative control) IFN-γ responses in both TB groups. Still, the Nil IFN-γ responses were lower than the TB antigen responses (p < 0.01), offering a conclusive test for half of the patients. We did not find any correlation between blood CD4 cell count and IFN-γ responses in pleural fluid.

Conclusion

The QFT-TB test in blood could contribute to the diagnosis of TB pleuritis in the HIV positive population. Still, the number of inconclusive results is too high to recommend the commercial QFT-TB test for routine use in pleural fluid in a TB/HIV endemic resource-limited setting.

Cytomegalovirus in the bronchoalveolar lavage fluid of patients with AIDS

This study investigated the significance of detecting cytomegalovirus in the bronchoalveolar lavage fluid of patients with human immunodeficiency virus infection. Bronchoscopy with BAL was performed on all patients. Lavage was examined for CMV by cytology, culture, and immunofluorescence. The lavage results were compared to clinical status at the time of bronchoscopy and the outcome of the respiratory event. Cytomegalovirus was detected in 51 percent of the BALs in the patients with HIV infection and 25 percent of the immunosuppressed patients without HIV. No association was found in the HIV infected patients between CMV and hypoxemia, abnormal chest roentgenogram, leukopenia, and increased mortality. As indicated by mortality, CMV did not significantly increase the severity of Pneumocystis carinii pneumonia. The study also suggested that CMV in BAL fluid reflected bronchopulmonary replication of the virus, and not contamination by virus in the blood. Cytomegalovirus does not appear to contribute directly to the pulmonary disease found in most patients with HIV infection.