Pattern recognition receptor (PRR), complement receptor, FcR

MHC class I molecules, MHC class II molecules

adhesion molecules, cytokine receptors, LPS receptors

Various cytokines, chemokines, complement components

Proteolytic enzymes, lysozyme, lysosomal enzymes, reactive oxygen species, NO, etc.

Devour, kill, digest

Antigen presentation

Inflammation

Immunomodulatory

tissue repair

Has powerful devouring and killing capabilities

Neutrophil extracellular trap

Constitutively expresses MHC-II class molecules and has strong antigen presentation effect

Include

Non-constitutively expresses MHC class II molecules and has weak antigen presentation ability

Including endothelial cells, fibroblasts, epithelial and mesothelial cells, etc.

1

2 Press the DC surface mark

commission antigen

Activate naïve T cells

Participate in the intrathymic differentiation and development of T cells

Immunomodulatory effect

induce immune tolerance

At the site of infection, MΦ presents antigen to effector Th cells

In lymph nodes and spleen, B cells present antigen to effector T cells

Purpose: To obtain the auxiliary effect of Th cells on B cell activation, proliferation and differentiation

Killer cell activating receptor (KAR)

Killer cell inhibitory receptor (KIR)

Inhibitory receptors on NK cells recognize MHC class I molecules (both classical and non-classical) and provide inhibitory signals to NK cells

Loss of self-molecules

Molecules expressed under abnormal conditions

NK cells can kill cells infected by viruses or intracellular bacteria early

Can kill tumor cells, especially blood-borne tumor cells

NK cells secrete IFN-γ, which can activate Mφ and promote the differentiation of CD4 T cells into Th1. NK cells secrete IFN-γ and TNF-α to promote DC maturation

IL-12 production by DC and Mφ during early infection stimulates NK cells to produce IFN-γ

NKT cells express both NK cell markers (human CD56) and T cell markers (TCR-CD3)

Mainly distributed in bone marrow, liver and thymus, etc.

NKT cells mainly recognize lipid antigens presented by CD1 molecules, and their recognition is not restricted by MHC

After activation, it secretes large amounts of IL-4, IFN-γ and other cytokines, participates in immune regulation, and has cytotoxic effects.

Most γδ T cells are CD4-CD8-double-negative cells, and a few are CD8 cells.

Mainly distributed in skin, mucous membranes and subcutaneous tissue

Recognize peptide antigens presented without APC processing and lipid antigens presented by CD1

Activated γδ T cells mainly exert cytotoxic effects

Activated γδT cells release cytokines IL-2, IL-4, IL-5, IL-6, GM-GSF, TNF-α and IFN-γ, etc., and exert immunoregulatory effects.

B1 cells differentiate from embryonic or early postnatal precursor cells.

B1 cells are mainly distributed in the thoracic cavity, abdominal cavity and intestinal wall lamina propria

B1 cells mainly recognize polysaccharides that are TI-2 antigens. They generally do not undergo high-frequency somatic cell mutations or antibody class switching. They mainly produce low-affinity antibodies of the IgM class and do not produce immune memory.