Natural killer cell defects resulting from thermal injury

Area of Science:

• Immunology
• Cellular Biology
• Oncology

Background:

• Peripheral blood mononuclear lymphocytes (PBL) play a crucial role in immune surveillance.
• Natural killer (NK) cells are vital for mediating spontaneous cytotoxic activity against tumor cells.
• Thermal injury can profoundly impact immune function, potentially leading to increased infection risk.

Purpose of the Study:

• To investigate the cytotoxic activity of NK cells in patients with thermal injuries.
• To determine if NK cell numbers or function are altered post-burn.
• To explore the correlation between NK cell activity and Leu-7 antigen expression.

Main Methods:

• Quantification of NK cell numbers using fluorescein isothiocyanate-conjugated antibody Leu-7 and an Ortho cell sorter.
• Assessment of spontaneous cytotoxic activity of PBL against K562 tumor cells at a 50:1 effector:target cell ratio.
• Evaluation of NK cell activity modulation by interferon-gamma and interferon-alpha.

Main Results:

• NK cell activity in burn patients was significantly reduced (30% of control levels).
• Burn patients' PBL showed a mean of 18% killing compared to 60% in controls.
• Interferon treatment enhanced NK activity in normal PBL but not in burn patients' PBL.
• Leu-7 antigen expression on PBL varied in burn patients, showing no clear correlation with NK activity.

Conclusions:

• Thermal injury severely impairs NK cell-mediated cytotoxicity.
• The reduction in NK activity is not directly correlated with the percentage of Leu-7 bearing cells.
• Impaired NK cell function in burn patients may contribute to their increased susceptibility to viral infections.