Introduction: Immune Response
An immune response is the reaction of an animal's immune system to foreign substances, such as viruses and bacteria. An immune response includes the production of specialized white blood cells and specific proteins called antibodies which seek out, neutralize, and destroy invading organisms.
Human white blood cell - phagocytosis
Human white blood cells engulf green fluorescent particles.

Elapsed time 5 minutes
A drop of blood was placed on a coverslip with a silicon spacer and diluted with saline solution. The drop was incubated at 37°C for 20 minutes, then red blood cells were washed away. A mixture of saline solution with human serum and opsonized yeast particles was used to cover the remaining cells. Images were taken on an upright inverted microscope with a 40x DIC objective at room temperature using a digital camera. Yeast pariticles have been colored green for visibility.