Modification of lymphocyte and monocyte functional activity by polymorphonuclear neutrophils in HIV infection

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• HIV infection significantly impacts the immune system, affecting various immune cells.
• Polymorphonuclear neutrophils (PMN) play a role in innate and adaptive immunity.
• The specific influence of PMN on immune responses in HIV-infected individuals requires further elucidation.

Purpose of the Study:

• To investigate the effect of PMN supernatants (PMNS) from HIV-infected patients on lymphocyte and monocyte function.
• To determine if PMNS from HIV patients differentially affect immune cells compared to healthy donors.

Main Methods:

• Supernatants from PMN of HIV patients and healthy donors were collected.
• The influence of these supernatants on lymphocyte proliferation, CD8 expression, NK-cell cytotoxicity, and antibody production was assessed.
• Monocyte function, including TNF-alpha production and phagocytosis, was also evaluated.
• The role of reactive oxygen species (ROS) and cytokines was investigated using specific inhibitors and antibodies.

Main Results:

• PMNS from HIV patients suppressed lymphocyte proliferation and down-regulated CD8 receptor expression.
• NK-cell cytotoxicity and antibody production (anti-HIV and IgG) were not significantly affected by PMNS.
• PMNS from HIV patients increased monocyte TNF-alpha production and phagocytosis, effects independent of ROS and major cytokines.
• The suppressive effects on lymphocytes were abrogated by catalase and superoxide dismutase treatment.

Conclusions:

• PMN from HIV-infected individuals exert a dual effect on the immune system, suppressing lymphocyte activity while enhancing certain monocyte functions.
• The observed effects on lymphocytes are mediated by ROS, while monocyte activation appears independent of ROS and common cytokines.
• These findings highlight the complex and potentially detrimental role of PMN in HIV pathogenesis.