Table 1.
Components of the Immune System
| Feature | Innate immunity | Adaptive immunity |
|---|---|---|
| Cells | Neutrophils Monocytes/macrophages Natural killer cells |
B lymphocytes T lymphocytes |
| Receptors | Expressed by all cells of a particular type (e.g., macrophages) Recognize broad classes of pathogens |
Clonal distribution on individual cells Highly specific |
| Soluble factors | Complement Mannose-binding lectin Chemokines Cytokines (including IL-1, TNF-α) |
Antibody Cytokines (including IL-2, IL-4, IL-5, IL-6, IL-10) |
| Change with repeated exposure to antigen | No | Yes (clonal expansion, memory lymphocytes) |