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Altered in vitro handling of Mycobacterium avium complex by monocytes and serum from HIV(+) patients
R P Swartz1, J A Roecklein, P F Pierce
1Department of Medicine, Georgetown University Medical Center, Washington, DC 20007, USA.
Abstract:
In patients with acquired immunodeficiency syndrome (AIDS), mycobacterial diseases are leading opportunistic infections. The reasons for the peculiar propensity for disseminated infection with Mycobacterium avium complex (MAC) remain unclear. We have previously examined, in detail, the ability of monocytes from healthy donors to take up and kill MAC under both nonopsonic and opsonic conditions. We have now evaluated the in vitro ability of peripheral blood monocytes from HIV(+) patients to take up and kill MAC organisms, and have discovered a reduced ability under both nonopsonic and opsonic conditions. This reduction is due to: 1) apparent defect(s) in the phagocytes themselves, and 2) substance(s) in the HIV(+) serum which actively suppresses phagocyte activity.
Insights
Patients with acquired immunodeficiency syndrome (AIDS) show reduced monocyte function against Mycobacterium avium complex (MAC). This impairment stems from both phagocyte defects and HIV serum
Area of Science:
- Immunology
- Infectious Diseases
- Virology
Background:
- Mycobacterial diseases, particularly Mycobacterium avium complex (MAC), are significant opportunistic infections in acquired immunodeficiency syndrome (AIDS) patients.
- The underlying mechanisms for the increased susceptibility to disseminated MAC infections in AIDS remain incompletely understood.
- Previous studies characterized MAC uptake and killing by monocytes from healthy individuals.
Purpose of the Study:
- To evaluate the in vitro phagocytic capacity of peripheral blood monocytes from HIV-positive patients against Mycobacterium avium complex (MAC).
- To identify factors contributing to the impaired ability of monocytes from HIV-positive individuals to control MAC infection.
Main Methods:
- In vitro assessment of peripheral blood monocyte function from HIV-positive patients.
- Evaluation of monocyte ability to uptake and kill MAC organisms under nonopsonic and opsonic conditions.
- Analysis of serum components from HIV-positive individuals for their effect on monocyte activity.
Main Results:
- Monocytes from HIV-positive patients demonstrated a reduced capacity to uptake and kill MAC organisms.
- This impaired phagocytic function was observed under both nonopsonic and opsonic conditions.
- The reduced efficacy is attributed to intrinsic defects in the phagocytes and the presence of inhibitory substances within HIV-positive serum.
Conclusions:
- Peripheral blood monocytes from HIV-positive individuals exhibit diminished phagocytic capabilities against MAC.
- Both intrinsic phagocyte defects and serum-derived suppressive factors contribute to the increased susceptibility to MAC infections in HIV/AIDS.
- Further research is warranted to elucidate the specific molecular mechanisms underlying these defects and to develop targeted interventions.