Table 4 Overview of the defining features of innate and adaptive immunity [1].
| Innate immune system | Adaptive immune system | |
|---|---|---|
| Cells |
Hematopoietic cells: • macrophages • dendritic cells • mast cells • neutrophils • basophils • eosinophils • NK cells • T cells • non-hematopoietic cells • epithelial cells (skin, airways, gastrointestinal tract) |
Hematopoietic cells: • T cells • B cells |
| Molecules |
cytokines • complement • proteins and glycoprotein |
antibodies (Ig) • cytokines |
| Response time | immediate | delayed by hours to days |
| Immunologic memory | none: responses are the same with each exposure | responsiveness enhanced by repeated antigen exposure |