macrophages
derived from myeloid progenitors
ingest pathogens through phagocytosis
present antigens via MHC class II molecules to activate T cells
activation:
- cytokine
- complement
- direct contact - leukocyte adhesion molecules
collections of activated macrophages that wall off microbes = granuloma
special types
- Kupffer cells - liver sinusoids
- Tissue macrophages - alveoli
- microglia - brain
- mesangial cells - kidney
- histiocytes - connective tissue
- Langerhans cells - skin
- dendritic cells