| A | B |
|---|
| infectious disease | a disease caused by a pathogen |
| pathogen | an agent that cuases a disease |
| immunity | resistance to a disease |
| immune system | a collection of cells, tissues, and organs that fight disease-causing agents |
| macrophage | an immune-system cell that engulfs pathogens |
| T cell | an immune-system cell that matures in the thymus |
| B cell | an immune-system cell that matures in bones and makes antibodies |
| antibody | a special protein that can recognize specific pathogens |
| memory B cell | an immune-system cell that "remembers" how to make a specialized antibody for a particular pathogen |
| allergy | an inappropriate immune-system reaction to a harmless antigen |
| autoimmune disease | a disease in which the immune system attacks the cells of the body it is meant to protect |
| cancer | a condition in which certain body cells begin dividing at an uncontrolled rate |
| noninfectious disease | a disease that cannot spread from one person to another |
