Neutrophil circulation and release from bone marrow during hypothermia

Area of Science:

• Physiology
• Immunology

Background:

• Neutrophils play a critical role in the immune system's response to infection.
• Hypothermia, or low body temperature, is a condition that can affect various physiological processes.

Purpose of the Study:

• To investigate the impact of hypothermia on neutrophil circulation and bone marrow release.
• To determine if hypothermia affects the body's ability to mobilize neutrophils in response to stimuli.

Main Methods:

• Pigs were subjected to hypothermia (29°C) or maintained at normothermia (37°C).
• Neutrophil counts (circulating mature and immature) were monitored.
• The response to catecholamines, hydrocortisone, and endotoxin was assessed under both temperature conditions.

Main Results:

• Core body cooling to 29°C led to a significant decrease in circulating neutrophils.
• Hypothermia impaired the bone marrow's ability to release neutrophils in response to steroid and endotoxin stimulation.
• Neutrophil demargination induced by catecholamines was not significantly affected by hypothermia.

Conclusions:

• Hypothermia compromises neutrophil circulation and release from bone marrow.
• Impaired neutrophil function during hypothermia may increase susceptibility to bacterial infections.