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.
Complement lysis
This movie illustrates the process of complement lysis, an immune response to bacterial infection. Antibodies to specific proteins on the bacterial wall attach themselves and sensitize the bacteria to an attack. Activation of the complement system results in explosion/lysis of the bacterial cells due to the influx of water through holes created in the bacterial cell wall.

In this movie, we have added complement (not visible) to sheep red blood cells that have already been sensitized with a specific antibody. In this example, the blood cells are playing the role of bacteria; you can watch the cells explode/lyse over time in a simulation of an attack on bacterial cells.

Elapsed time about 2.5 minutes.
To mimic the explosion/lysis of bacteria, sheep red blood cells (sRBC's) were sensitized with commercially available antibodies so that they would lyse when attacked by complement. sRBC's are mixed with commercially available complement, then immediately mounted between a slide and coverslip and heated to 37°C. Images were taken on an upright compound microscope using a digital camera and 40x DIC objective.