Mast cells migrate from blood to brain.

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Mast cells (MCs) are present in the CNS across species.
• MC numbers can rapidly increase in adult brains due to physiological changes.

Purpose of the Study:

• To investigate the mechanism behind increased mast cell populations in the brain.
• To test the hypothesis that mast cells migrate into the neural parenchyma.

Main Methods:

• Purified rat peritoneal mast cells were vital dye-labeled and injected into host rats.
• Mast cell migration across thalamic blood vessels was assessed using confocal microscopy.
• Localization of donor mast cells relative to basal lamina and astrocytes was determined.

Main Results:

• Injected mast cells, containing histamine or serotonin, were found near thalamic blood vessels within one hour.
• Confocal microscopy confirmed dye and mediator co-localization within single cells.
• Mast cells were observed deep to the basal lamina, within glial processes, indicating penetration of the blood-brain barrier.

Conclusions:

• This study provides the first evidence of rapid mast cell penetration of brain blood vessels.
• Mast cell migration into the CNS parenchyma may explain rapid increases in brain mast cell populations following physiological stimuli.