Changes

A memory cell is a group of cells that help the body defend itself against [[disease]] by remembering prior exposure to specific organisms (e.g. [[viruses]] or [[bacteria]]).  Therefore these cells are able to respond quickly when these organisms repeatedly threaten the body.

A memory cell is a group of cells that help the body defend itself against [[disease]] by remembering prior exposure to specific organisms (e.g. [[viruses]] or [[bacteria]]).  Therefore these cells are able to respond quickly when these organisms repeatedly threaten the body.<ref>http://www.cdc.gov/vaccines/about/terms/glossary.htm#m</ref>