It has been known for a while that some drugs seem to have physical rather than chemical modes of action or associated side effects. Glucocorticoid drugs that are used for asthma or rheumatoid arthritis, for example, increase the white blood cell count but biological explanations for how that happens have been unconvincing.
Researchers from Georgia Tech and Emory University have decided to investigate whether physical processes may be at play, and so they built a microfluidic model blood vessel system that can replicate the forces experienced by white blood cells in the smallest of capillaries within our bodies.
The device is a polymer chip that passes real human blood through a very narrow passage, allowing both the drugs tested and natural physical forces to impact the life of white blood cells swimming through. The investigators used an atomic force microscope to analyze the stiffness of the white blood cells before and after they go through the device.
What they discovered is that the drugs cause the white blood cells to soften, changing how they flow through vessels. In particular, the softening caused the cells to move away from the vessel walls and flow down the center, effectively increasing their count.
Study in Proceedings of the National Academy of Sciences: Cellular softening mediates leukocyte demargination and trafficking, thereby increasing clinical blood counts…
Via: Georgia Tech…