Do macrophages have complement receptors?

The complement receptors on macrophage are responsible for their binding and ingestion of opsonized targets. The two established receptors are CR1, which recognizes C3b, and CR3, which recognizes iC3b, the natural product of C3b from cleavage by the complement control protein factor I and its cofactors.

What are the receptors on macrophages?

The major chemokine receptors on macrophages are CCR2, CCR5, and CX3CR1 (130, 131). CCR2 binds CCL2 and related chemokines of the MCP subfamily and is responsible for release of monocytes from the bone marrow and their trafficking to inflamed tissues.

Which complement receptor is involved in mediating phagocytosis?

Complement Receptor 3 (CD11b/CD18) Mediates Type I and Type II Phagocytosis During Nonopsonic and Opsonic Phagocytosis, Respectively | The Journal of Immunology.

How are complement proteins involved in phagocytosis?

Complement Mediated Phagocytosis Background Particularly, complement-mediated phagocytosis is accomplished by specific recognition of bound complement components by the corresponding complement receptors on the phagocytes. Pathogen invasion leads to the generation of C3 convertase which yields C3b.

Where are complement receptors found?

Complement receptor type 3 (CR3, Mac-1, and CD11b/CD18) is found on monocytes, neutrophils, natural killer (NK) cells, and dendritic cells. CR3 is composed of α and β chains. The CD11b receptor interacts with cell-bound iC3b to initiate phagocytosis.

Do all cells have complement receptors?

White blood cells, particularly monocytes and macrophages, express complement receptors on their surface. Complement receptor (CR) 1, 3, and 4 function as opsonins which stimulate phagocytosis, whereas CR2 is expressed only on B cells as a co-receptor.

What are the different types of macrophages?


Type of macrophage Location
Alveolar macrophage Lung alveoli
Kupffer cells Liver
Microglia Central nervous system
Splenic macrophages (marginal zone, metallophilic and red pulp macrophages) Spleen marginal zone, red and white pulp

What happens to macrophages after phagocytosis?

After phagocytosis, macrophages and dendritic cells can also participate in antigen presentation, a process in which a phagocyte moves parts of the ingested material back to its surface. This material is then displayed to other cells of the immune system.

What can complement receptors 1 and 2 bind to?

Complement receptors type one (CR1; C3b/C4b receptor; immune adherence receptor; CD35) and type two (CR2; C3d receptor; EBV receptor; CD21) interact with derivatives of C3 (CR1 and CR2) and/or C4 (CR1) in immune complexes (IC) (20).

What do complement receptors bind to?

A complement receptor is a membrane-bound receptor belonging to the complement system, which is part of the innate immune system. Complement receptors bind effector protein fragments that are produced in response to antigen-antibody complexes or damage-associated molecules.

Why are macrophage complement receptors important to host immune response?

However, macrophage phagocytic receptors recognize C3b and its fragments preferentially. Due to the versatility of the ester‐bond formation, C3‐mediated opsonization is central to pathogen recognition and receptors for the various C3 degradation products therefore play an important role in the host immune response ( Holers et al ., 1992 ).

What are the names of the complement receptors?

There are now three recognized gene superfamilies of complement receptors: The short consensus repeat (SCR) modules that code for CR1 and CR2, the β 2 integrin family members CR3 and CR4, and the immunoglobulin Ig‐superfamily member CRIg.

Is the complement system part of the immune system?

A complement receptor is a receptor of the complement system, part of the innate immune system. Complement receptors bind proteins of the complement system, and can thus detect pathogens without mediation by antibodies.

How are complement receptors used in pathogen clearance?

Complement component C3 is central to opsonization. Its first cleavage product, C3b, forms the multisubunit enzyme, C3bBb, which proteolytically cleaves additional C3 molecules on the pathogen surface. C3b is further degraded to iC3b, C3c and C3dg, products that serve as ligands for selective complement receptors on leukocytes.