A filtration model for study of leukocyte transit in the microcirculation

Area of Science:

• Hematology
• Biophysics
• Physiology

Background:

• Leukocyte behavior in microcirculation is crucial for immune response and disease.
• Understanding factors affecting leukocyte flow is vital for studying inflammatory and vascular conditions.

Purpose of the Study:

• To characterize an in vitro filtration model for assessing leukocyte flow dynamics.
• To identify key parameters influencing leukocyte filtration and passage through microvessels.

Main Methods:

• Utilized in vitro filtration of normal human peripheral blood leukocytes through 8 µm pore size filters.
• Investigated the effects of EDTA, temperature, hydrostatic pressure, pH, and osmolarity on leukocyte filtration.
• Assessed the impact of leukocyte deformability (formalin fixation) and cell-cell interactions (with erythrocytes) on flow.

Main Results:

• Optimal filtration conditions identified: 0.2% EDTA, 10 cm hydrostatic pressure, neutral pH, isotonicity, room temperature.
• High leukocyte concentrations (>25 X 10^9/L) significantly slowed filtration.
• Reduced leukocyte deformability markedly impaired filtration.
• Interactions with erythrocytes paradoxically enhanced leukocyte transit.

Conclusions:

• The developed in vitro model effectively characterizes leukocyte flow properties.
• Leukocyte deformability and interactions with other blood cells are critical determinants of microcirculatory flow.
• This model system can be applied to study both normal and pathological leukocyte behavior in microcirculation.