Table 1.
Comparison of sources and functions of C1 related components.
| C1 component | Chromosome (human) | Primary sources | Other Sources | Stimulation | Function |
|---|---|---|---|---|---|
| C1q | 1p34.-1p36.3 (27) | Tissue resident macrophages > Infiltrating macrophages; Immature dendritic cells (27–31) | Epithelial cells, Endothelial cells (32) |
IFNγ1 (27) | Pattern Recognition (13, 14); Binds antibodies (18–20) |
| C1r/C1s | 12p13.31 (26, 33) | Liver (33) | Epithelial cells, Macrophages (34–36) | IFNγ (36) | Serine proteases that cleave C4 and C2; Stabilize C1q binding to antibodies (15) |
| C1 inhibitor | 11q11-q13.1 (37) | Liver (37) | Monocytes, Macrophages, Endothelial Cells (34) | IFN types I and II, IL-6, IL-1, and TNFα (34, 37) | Serine protease inhibitor (serpin) (38) |
1Modulation of C1q expression has been tested in peritoneal macrophages and cultured human macrophages, but not in tissue resident macrophages.