Table 1. Fcγ-receptors in human and mouse.
| Activatory | Relative | Structural signalling | Allelic | Putative functional murine |
Principal effector-cell expression profilea
|
||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Receptor | CD | inhibitory | affinity for IgG | components | variants | analogue | mΦ | DC | N | B | NK |
| Human | |||||||||||
| FcγRI | CD64 | Activatory | Highb | ITAM (associated γ-chain) | FcγRI | • | • | • | |||
| Fcγ RIIa | CD32a | Activatory | Low/Mod | ITAM (integral) | 131H 131R | FcγRIV | • | • | • | ||
| Fcγ RIIb | CD32b | Inhibitory | Low/Mod | ITIM (integral) | 232I 232T | FcγRIIb | • | • | • | • | |
| Fcγ RIIc | CD32c | Activatory | Low/Mod | ITAM (integral) | • | • | • | ||||
| Fcγ RIIIa | CD16a | Activatory | Low/Mod | ITAM (associated γ-chain) | 158V 158F | FcγRIII | • | • | • | ||
| Fcγ RIIIb | CD16b | Activatory | Low/Mod | Non-signalling (gpi-linked) | NA1 NA2 | • | |||||
| Mouse | |||||||||||
| FcγRI | Activatory | High | ITAM (associated γ-chain) | • | • | ||||||
| FcγRIIb | Inhibitory | Low/Mod | ITIM (integral) | • | • | • | • | ||||
| FcγRIII | Activatory | Low/Mod | ITAM (associated γ-chain) | • | • | • | • | ||||
| FcγRIV | Activatory | Low/Mod | ITAM (associated γ-chain) | • | • | • | |||||
Abbreviations: DC=dendritic cell; ITAM=immunoreceptor tyrosine-based activatory motif; ITIM=immunoreceptor tyrosine-based inhibitory motif; mΦ=macrophage; N=neutrophil, B=B cell; NK=natural killer cell.
a
Fc-receptor expression is variable and can be modulated on certain cell populations, for example, by cytokine signalling and activation status. Data shown are intended to indicate expression on key effector-cell populations involved in Fc-mediated immune responses.
b
Human and murine FcγRI have high affinity for monomeric IgG irrespective of antigen binding.