Common cell surface markers are the following:
CD3 which is a T cell receptor coreceptor.
CD4 molecule is a relatively non-polymorphic, 55 kDa surface glycoprotein comprised of four extracellular domains, a hydrophobic transmembrane region and a hydrophilic cytoplasmic tail. The NH2 terminal extracellular domain (V1) has striking sequence homology to Ig light china variable retions. The other extracellular domains (V2-V4) are hoologous to other members of the Ig gene superfamily. CD4 is expressed mainly on T helper lymphocyte subsets which recognize peptide antigens bound to Class II MHC molecuels. The NH2 erminal domain of CD4 also contain binding residues most important in the interaction of CD4 with gp120, the envelope glycoprotein of HIV. (Lederman “A single amino acid substitution in a common african allele of the CD4 molecule ablates binding of the monoclonal antibody, OKT4” Molecular Immunology, 28(11) pp. 1171-1181, 1991).
CD11a is a member of the ?2 family.
CD11b is a member of alpha-chain integrin and form a complex with alpha2-integrin as Mac-1. CD11b is expressed on neutrophils, monocytes, NK cells and a subset of CD8+ T cells. It plays a central role in mediating migration of leukocytes from peripheral blood to sites of inflammation during the process of host defense. It contributes to form leukocyte adhesion, not only to the endothelium via the but also to the underlying subendothelium and interstitial extracellular matrix by binding diverse kinds of ligands, such as fibronectin, collagens, and laminins. CD11b is a marker that defines and indicates cellular electated levels of activated neutrophils, activated monocytes, activated T-lymphocytes, activated basophils and/or activated mast cells.
The catechin, EGCG decreases flow cytometric CD11b expression on periopheral blood CD8+ T cells as a fesult of binding to CD11b.
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CD11c is a member of the ?2 integrin family.
CD16 which is a receptor present on for the Fc region of IgG.
CD20: (also called human B-lymphocyte-restricted idfferentiation antigen or Bp35) is a hydrophobic transmembrane protein with a MW of aobut 35 kD located on pre-B and mature B lymphocytes. CD20 is found on the surface of more than 90% of B cells from peripheral blood or lymphoid organs and is expressed during ealry pre-B cell development and remains until plasma cell differentiation. CD20 is present on both normal B as well as malignant B cells. In particular, CD20 is expressed on more than 90% of B cell non-Hodgkin’s lymphomas (NHL) but is not found on hematopoietic stem cells, pro-B cells, normal plasma cells or other normal tissues (US2009/0162352).
CD24 (Heat-stable antigen or HSA) is a small glycosyl-phosphoinositol-anchored cell surface protein that is able to provide costimulatory signals to T cells and has been implicated in the development of autoimmune disease. However, CD24 in association with Siglec10 has been shown to selectively repress inflammatory response to danger associated molecular patterns (DAMPs). CD24 has no known mechanisms for signal tranduction and its anti-inflammatory response is due to the fact that siglecs are cell surface receptors which can interact with CD24 (US 8,163,281). More than 90% of the mass of CD24 is stimated to be derived from glycosylation.
CD35 (CR1) which is a receptor present on B cells
CD25 is considered a marker of activation.
CD28 which is a T cell receptor for B7 molecule on an antigen presenting cell. CD28 is a disulfide-linked homodimer on the surface of T cells which binds to members of the B7 family on APCs and costimulates T cell activation. In humans, all thymocytes and the vast majority of cord blood CD8+ T cells express CD28. The proportion of CD8+ T cells that lack surface epxression of CD28 increases with age, so that in adulthood, 25-50% of CD8+ T cells are CD28-. In advancing HIV infection, more than 50% of CD8+ T cells are CD28-. CD25+ phenotype suggests central membory cells.
CD29 is a ?1-integrin.
CD30 is a member of the .
CD40 along with TNF? is involved in the differentiation of DCs from CD34+ bone marrow or cord blood progenitors. CD40 is expressed on. Its ligand, CD40L, is expressed on . The interaction between CD40 and CD40L increases DC survival, upregulates MHC and costimulatory molecule expression, and induces the expression of a variety of cytokines (e.g.,) in DCs. CD40/CD40L-mediated contacts between B and T cells are required for the generation of T cell-dependent humoral immune respones. Activation of CD40 on B cells stimulates proliferation and mediates Ig class switching in conjunction with IL-4 and Il-13.
CD44: is the major receptor for hyaluronan.
CD45RA is expressed on both naive and antigen-primed effector CD8 T cells.
CD45RBlow express the phenotype of antigen-experienced cells.
CD45RO is expressed predominantly on activated CD8 T cells. Thus CD45RO is usually associated with cells that have experienced antigen and are often referred to as memory cells.
CD58 is a co-stimulatory molecule which has recently been shown to stimulate the production of IL-10 by human T cells.
CD62L L-selectin expression is down-regulated upon activation.
CD66: family members appear to play a role in a wide variety of normal and pathological processes. CD66 monoclonal antibodies (mAbs) react with members of the carcinoembryonic antigen (CEA) family. In the CD terminology, mAbs belonging to the CD66 cluster are classified according to their reactivity with each family member, as indicated by a lower case letter after “CD66” as follows: CD66a, CEACAM-1 or biliary glycoprotein (BGP); CD66b, CEACAM-8 or CGM6; CD66c, CEACAM-6 or NCA; CD66d, CEACAM-3 or CGM1; CD66e, CEA and CD66f, preganancy specific glycoprotein (PSG).
CD69 is considered an early activation marker.
CD70: costimulates CD4+ T cells to produce IL-2 and IFNy and cross0linking of CD70 also upregulates the expression of CD154 on activated T cells.
CD89 (FcalphaR1): is a membrane glycoprotein that contains two extracellular Ig like domains (206 aa), a membrane spanning region (19 aa) and a cytoplasmic tail (31 aa). Like other Fc receptors lacking an intracellular signaling motife, CD89 signaling into the cell is initiated via its association with the FcRgamma-chain. The FcRgamma-chain is a homodimer signaling unit with a size of 10 kDa. Binding to CD89 leads to phosphorylation of the intracellular, immunoreceptor tyrosin based activation motif (ITAM) on the gama chain, activating the signaling pathways downstream.
CD89 binds both the monomeric and dimeric forms of IgA1 and IgA2. It is expressed only by myeloid cells, including neutrophils, monocytes, macrophages, and eosinophils.
CD93 (C1qRp): is a type 1 transmembrane glycoprotein located on chromosome 20 in humans. It is composed of 652 amino acids including leader sequence, c-type carbohydrate-sensing domain, 5 EGF-like domains, mucin domain, one transmembrane domain and an intracellular domain of 47 amino acids. CD93 is expressed in myeloid lineages, hematopoietic stem cells, NK cells, platelets, microglia and endothelial cells. Human CD93 is a receptor for complement component 1, subcomponent q phagocytosis (C1qRp). It was originally reported to be involved in the C1q mediated enhancement of phagocytosis in innate and adaptive immune response.
A soluble form of the CD93 that retain the N terminal carbohydrate recognition domain and the epidermal growth factor repeats after ectodomain cleavage has been detected in human plasma (Bohlson, J. Immunology, 2005, 175: 1239-1247) and well as in synovial fluid from rheumatoid arthritis patients (Young, WO/2010/087594; US 13/146876).
CD95 indicates a memory pehnotype.
CD122 (IL-2 receptor beta chain)
CD137 (4-1BB): is a membrane glycoprotein that is inducibly expressed on activated T cells, B cells, DCs and NKs. It is a member of the TNFR superfamily of costimulatory molecules. Stimulation of CD137 by its natural ligand, CD137L, or by agonistic antibody induces vigorous T cell proliferation and prevents activation induced cell death. The intracellular biochemical pathway for CD137 signaling is not fully understood, but TNFR associated factors (TRAF) 1 and 2 are believed to play a role. CD137-induced signals lead to the recruitment of TRAF family members and activation of several kinases, including ASK-1, MKK, MAPK3/MAPK4, p38, and JNK/SAPK. Kinase activaiton is then followed bythe activation an nuclear translocation of several transcription factors, including ATF-2, Jun, and NF-kB. Anti-human CD137 antibodies are potential biotherapeutic agents to shrink solid tumors in vivo and prevent their recurrence.
CD152 (CTLA)-4: is a high affinity counterreceptor of B7-1 and B7-2 that delivers a negative signal and inhibits T cell proliferation, IL-2 production and cell cycle progression.
CD200 (OX-2): is a highly conserved type I transmembrane glycoprotein expressed on the surface of numerous cell types including B cells, some T cells and DCs. The protein interacts with its receptor CD200R which is largely restricted to cells of the myeloid lineage, including monocyte macrophages, DC, and microglia as well as CD4+ T cells, especially polarized Th2 cells. There are at least two potentially activaitng isoforms of the receptor, designated mCD200RLa and mCD200Lb which do not bind to CD200 and have unknown ligands, but, in common with other receptor pairs, they have potential activating function through DNAX-activating protein-12 (DAP-12) adapter protein binding. The CD200:CD200R interaction has been thought to deliver an immunodulatory signal to cells and induce immunosuppression including apoptosis-associated immune tolerance.
While certain reports show that CD200 has the capacity to modulate myeloid cell activity in an inhibitory manner and delivery and inhibitory signal, other reports have shown that CD200, which has sequence homology to B7.1 and B7.2 molecules, functions as a co-stimulatory molecule to induce T cell proliferation. Thus similar to other described negative co-receptors, CD200 may exert different effects at different points in the immune response.
The CD200R is structurally related to CD200, located on the same chromosome and the genes probably evolved by gene duplication. CD200R is distinct in that it displays a longer cyoplasmic tail containing three conserved tyrosine reisudes, one of which is contained with an NPXY motife. Upon ligand or agonist antibody binding, CD200R is phosphorylated on the tyrosine of the NPXY motife and subsequently binds adapter proteins Dok1 and Dok2. Phosphorylation of these adapter proteins recruits SHIP and RasGAP, which subsequently inhibits the Ras/MAPK activation pathways.