Table 1 Summary of human Siglec family members, their expression, functions, similarities and differences

Siglec-1(CD169)

Macrophage,monocytes, mature dendritic cells

α2,3 > α2,6

Adhesion Cell–cell interaction

Mediates antigen presentation; inhibits the proliferation of tumor-asscociated T cell; affects TAMs' function

Cancer,autoimmunity, SLE,infectious disease

[8, 18]

Siglec-2(CD22)

B cells

α2,6

Inhibition

B cell differentiation and tolerance

Lymphoma, leukemia, SLE, sepsis, RA

[8, 19]

Siglec-3(CD33)

Myeloid progenitors, macrophage, monocytes, microglia

α2,6 > α2,3

Adhesion Inhibition

Induces apoptosis; inhibits the killing effect of NK cells; regulates myeloid cell proliferation and differentiation

AML, AD

[8]

Siglec-4(MAG)

Myelin producing cells (Oligodendrocytes, Schwann cells)

α2,3 > α2,6

Adhesion Inhibition

Adjusts axons

Neuro-degeneration

[8, 20]

Siglec-5(CD170)

Monocytes, neutrophils, B cells, activated T cells

α2,3

Inhibition

Delivers an anti-inflammatory signal; inhibits immune cell activation

GBS infection, neutrophil disorders

[8, 20]

Siglec-6(CD327)

Trophoblasts, mast cells, B cells, circulating T cells

α2,6

Inhibition

Decrease cytotoxic functions of effector CD8 + T cells; suppress trophoblast invasivenes

Cancer, pre-eclampsia, allergy

[8, 21,22,23]

Siglec-7(CD328)

NK cells, monocytes, mast cells, platelets, activated T cells

α2,8 > α2,6 > α2,3

Binding Inhibition

Inhibits the killing effect of NK cells; inhibits inflammatory responses of mast cells and basophils

Cancer, HIV infection, allergy

[24, 25]

Siglec-8

Eosinophils, mast cells, basophils

α2,3 > α2,6

Inhibition Apoptosis

Induces eosinophils apoptosis

Allergy, asthma

[8, 24]

Siglec-9(CD329)

NK cells, monocytes, macrophages, dendritic cells, neutrophils, activated T cells

α2,3 = α2,6, or sulfated ligands

Inhibition Apoptosis

Promotes tumor angiogenesis; inhibit the proliferation and activation of TAM,NK cells and neutrophils

Cancer, asthma, sepsis, COPD, RA

[24, 26, 27]

Siglec-10

B cells, NK cells, monocytes, CD4 + T cells

α2,3 = α2,6

Inhibition Bind to CD24

Induces apoptosis; inhibits the proliferation and activation of tumorassociated T cells and TAM

Cancer, sepsis, allergy

[27, 28]

Siglec-11

Macrophages, microglia

α2,8

Inhibition

Reduced inflammatory response; inhibits microglial activation

Neuro-inflammation, AD

[24]

Siglec-14

Monocytes, neutrophils

α2,3

Activation, Polymorphism

Recognizes bacterial pathogens, elicits pro-inflammatory responses

SLE, COPD, GBS infection,

[8, 20]

Siglec-15

Osteoclasts, macrophages

α2,6 or sialyl-Tn

Activation Inhibition

Modulation of osteoclast differentiation and bone resorption; immune modulation of tumorassociated T cells and TAM

Osteoporosis, cancer

[24, 29, 30]

Siglec-16

Macrophages

α2,8

Activation, Polymorphism

Unkown

Schizophrenia

[24]