myeloid cell types

It is a single-pass type I membrane protein and contains 4 TNFR-Cys repeats. The protein is a member of the tumor necrosis factor (TNF) family of receptors. It is expressed on the surface of most cell types, including cells of epithelial and myeloid lineages, but not on T and B lymphocytes. The protein is the receptor for the heterotrimeric lymphotoxin containing LTA and LTB, and for TNFS14/LIGHT. It promotes apoptosis via TRAF3 and TRAF5 and may play a role in the development of lymphoid organs. The encoded protein and its ligand play a role in the development and organization of lymphoid tissue and transformed cells. Activation of the encoded protein can trigger apoptosis. Not only does the TNFRSF3 help trigger apoptosis, it can lead to the release of the cytokine interleukin 8. Overexpression of TNFRSF3 in Human Cells cells increases IL-8 promoter activity and leads to IL-8 release. TNFRSF3 is also essential for development and organization of the secondary lymphoid organs and chemokine release.

CD48 is a GPI-linked protein in the CD2 family of immunoglobulin superfamily proteins. CD48 is expressed on most lineage-committed hematopoietic cells but not on hematopoietic stem cells or multipotent hematopoietic progenitors. Among dendritic cells (DC), CD48 is selectively expressed on circulating myeloid DC and resident bone marrow and thymus DC. CD2, 2B4, and heparan sulfate function as CD48 ligands. CD48 is competent to transduce signals and can also trigger signaling through CD2 or 2B4. CD48 expressed on NK cells is coactivating, whereas CD48 expressed on other cell types inhibits NK cell activation.

Trem-like transcript 1 protein, also known as Triggering receptor expressed on myeloid cells-like protein 1, TREML1 and TLT-1, is a cytoplasm and single-pass type I membrane protein. TREML1 / TLT-1 is expressed exclusively in platelets and megakaryocytes (MKs) and that its expression is up-regulated dramatically upon platelet activation. It is a receptor that may play a role in the innate and adaptive immune response. TREML1 / TLT-1 contains the characteristic single V-set immunoglobulin (Ig) domain, its longer cytoplasmic tail is composed of both a proline-rich region and an immune receptor tyrosine-based inhibitory motif, the latter known to be used for interactions with protein tyrosine phosphatases. The triggering receptors expressed on myeloid cells (TREMs) have drawn considerable attention due to their ability to activate multiple cell types within the innate immune system, including neutrophils, monocyte / macrophages, and dendritic cells, via their association with DAP12. TREML1 / TLT-1 is prepackaged, along with CD62P, into both MK and platelet alpha-granules. Differences in thrombin-induced redistribution of CD62P and TREML1 indicate that TREML1 is not simply cargo of alpha-granules but may instead regulate granule construction or dispersal. TREML1 / TLT-1 does not function to inhibit members of the TREM family but instead may play a role in maintaining vascular hemostasis and regulating coagulation and inflammation at sites of injury.

Clec4b2, also known as mDCAR1, is a member of the DCIR/DCAR family. Expression of Clec4b2 was strongly tissue dependent. Clec4b2 expression on DCs was restricted to the CD8(+) DC subset in spleen and thymus and on subpopulations of CD11b(+) myeloid cells in bone marrow and spleen, whereas the molecule was not detectable on both cell types in lymph nodes and peripheral blood. Clec4b2 is a functional receptor on cells of the immune system and provides further insights into the regulation of immune responses by CLRs.