| A | B |
|---|
| T-cell | Lymphocyte produced in the thymus |
| B-cell | Lymphocyte produced in bone marrow |
| Leukocyte | General term for a white blood cell |
| Cytokine | "Hormone" of the immune system |
| Pathogen | Any disease-causing organism |
| Antigen | Protein found on a pathogen that triggers an immune response |
| Antibody | Protein produced by a B-cell that binds to specific pathogens |
| Thymus | Immune organ that lies beneath the sternum |
| Spleen | Largest immune organ in the abdomen |
| Lymph | Body fluid |
| Macrophage | Large immune cell that "swallows" pathogens |
| Helper T-cell | T-cell that regulates the immune response |
| Killer T-cell (cytotoxic T-cell) | T-cell that kills cells infected with viruses |
| Phagocyte | Immune cell that engulfs and digests pathogens |
| Granulocyte | Immune cell that releases toxic chemicals onto pathogens |
