The innate immune system is the first line of defense against foreign pathogens.
Non-cellular components of the innate immune response include:
- Intact skin/mucosal linings
- Cilia within the lungs
- Tears and sweat
- Lysozyme
- Complement
- Interferons (alpha, beta, and gamma)
Cellular components of the innate immune response include:
- Neutrophils - phagocytic WBCs
- Basophils - mediate allergic and hypersensitivity reactions by secreting histamine and heparin. IgE binds to a receptor found on basophils.
- Eosinophils - associated with parasitic infections and allergic reactions. Eosinophils down-regulate basophil activity.
- Monocytes/macrophages - phagocytic WBCs in the blood and tissues, respectively. Macrophages can play a role in antigen presentation to activate the adaptive immune response.
- Natural killer cells - type of lymphocyte that monitors intracellular activities of other cells that have a loss or decreased expression of MHC class I typically associated with viral infections or cancer.
- Dendritic cells - a type of antigen-presenting cell.
To learn about neutrophils and monocytes/macrophages, click the More Info button below.
