Modification of lymph during passage through the lymph node: effect of histamine

Area of Science:

• Physiology
• Immunology
• Vascular Biology

Background:

• Histamine is a key mediator in inflammatory and immune responses.
• Its role in modulating lymph composition during passage through lymph nodes is not fully understood.
• Lymph nodes play a critical role in fluid balance and immune surveillance.

Purpose of the Study:

• To evaluate the effect of histamine on the fluid and protein content of lymph.
• To determine if histamine alters lymph composition during passage through the canine popliteal lymph node.

Main Methods:

• Utilized a canine perfused popliteal lymph node preparation.
• Perfusion with artificial lymph of known composition (3.71 g/100 ml albumin).
• Analyzed efferent lymph for changes in volume and protein concentration after histamine infusion (2-4 µg base/ml).

Main Results:

• Histamine infusion significantly increased efferent lymph flow by 35.3% (P < 0.05).
• Efferent lymph protein concentration increased by 15.2% (P < 0.05).
• Protein flux increased by 58.0% (P < 0.05), with evidence of plasma proteins entering efferent lymph.

Conclusions:

• Histamine alters lymph composition by increasing fluid and protein content.
• The source of increased fluid and protein is likely the nodal vasculature.
• Findings suggest histamine's role in modulating lymph dynamics and its potential impact on immune cell trafficking.