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Table 1 Salient characteristics of Fcγ Receptors [38, 4043]

From: Bench-to-bedside review: Immunoglobulin therapy for sepsis - biological plausibility from a critical care perspective

  Fcγ receptors
Characteristics FcγRIA FcγRIIA FcγRIIC FcγRIIIA FcγRIIIB FcγRIIB
Function Activatory Activatory Activatory Activatory Activatory Inhibitory
Affi nity to IgG High Low Low Low Low Low
IgG subtype affinity IgG1 >>> IgG3 = IgG4 = IgG2 IgG1 = IgG3 >> IgG2 > IgG4 IgG1 > IgG3 > IgG4 >> IgG2 IgG1 >> IgG3 = IgG2 > IgG4 IgG1 = IgG3 >> IgG2 = IgG4 IgG1 > IgG3 > IgG4 >> IgG2
Cell type receptor Monocytes, macrophages, neutrophils, eosinophils, dendritic cells Monocytes, macrophages, neutrophils, dendritic cells, platelets Natural killer cells Monocytes, macrophages natural killer cells, dendritic cells Neutrophils, eosinophils, basophils Monocytes, macrophage mast cells, B cells, plasma cells, neutrophils, basophils, dedritic cells
Binding IgG Only to IgG immune complexes     
Signal transfer ITAM ITAM ITAM ITAM ITAM ITIM
Other characteristics   1. Immune response to streptococcal infection    1.Glycosylphosphatidyl-inositol-linked receptor that has no cytoplasmic domain 1. Regulates B-cell activation and plasma cell survival
   2. Low affi nity to IgG2 isoform - FcγRIIA-R131 homozygous state predisposes to infection     2. Basal level inhibition to dendritic cell maturation
       3. Polymorphisms important in malaria
  1. FcγR, Fcγ receptor; Ig, immunoglobulin; ITAM, immunoreceptor tyrosine-based activating motif; ITIM, immunoreceptor tyrosine-based inhibitory motif; IVIg, polyvalent intravenous immunoglobulin.