Flow Cytometry FAQs

Yes they are. CD8 and CD8α are widely used markers for identifying cytotoxic T lymphocytes (CTLs). CD8 plays an important role in mediating the recognition and excution funtions of CTLs. CD8α is a subunit of CD8 complex, which means the α chain, and it is quite important in the formation of the complex. CD8α chain not only participates in the binding with MHC-I molecules, but also regulates the activity of CTLs by interacting with other signal molecules. Therefore, the expression level and functional status of CD8α can be used for evaluating the activation and effection of CTLs, as well as CD8.

CD4 (domain1) is not the same as CD4, it means the first domain of CD4 protein, also known as D1 domain or Ig-likeV-type domain, so it can be used as a substitution of CD4.
CD4 (cluster of differentiation 4) protein, a surface molecule of immune cells which is often used to identify and label helper T lymphocytes (CD4+T cells), consists of four domains, including an extracellular domain, a transmembrane domain and an intracellular domain.

Yes, it is. CD44H is one of the common names for CD44. CD44 (cluster of differentiation 44) is an immune cell surface molecule, also known as Hyaluronate receptor. The CD44 protein is diverse through the presence of multiple variant shear forms (isoforms). Among them, CD44H is the standard form of CD44, which is the main variant shear form of CD44. CD44H interacts with components of the extracellular matrix, such as hyaluronan, and is involved in biological processes such as cell adhesion, migration, and signaling. CD44H is widely expressed in many cell types and has important functions in immune cells, tumor cells, and stem cells. It is important to note that different CD44 variant cut forms may have different functions and expression patterns. Therefore, in specific studies or experiments, it may be necessary to further distinguish and study specific CD44 variant shear forms (such as CD44v6, CD44s, etc.).

Yes, it is. CD3 consists of 5 different chains, namely gamma, delta, epsilon, zeta, and eta chains. Almost all anti-CD3 monoclonal antibodies target the epsilon chain, which only expressed in T cells normally.

No, they are not. CD45.1 and CD45.2 are subtype marker forms on the surface of immune cells and belong to the CD45 (cluster of differentiation 45) family. CD45 is a receptor protein tyrosine phosphatase, widely expressed in a variety of immune cells, such as T cells, B cells, macrophages and so on. CD45 exists in several subtypes, including CD45.1 and CD45.2. These two subtypes are mainly determined by different alleles on the CD45 gene. In experiments, the introduction of alleles of CD45.1 or CD45.2 can be used to distinguish between cells of different origin. The mouse strains expressing CD45.1 include FVB, RIII, SJL/J, STS/A, DA, etc. The mouse strains expressing CD45.2 included AKR, BALB/c, CBA/Ca, CBA/J, C3H/He, C57BL, C57BR, C57L, C58, DBA/1, DBA/2, NZB, SWR, 129, etc.

CD90, also known as Thy1 (thymus cell antigen 1), is a mouse immune cell surface molecule. In mice, there are two main subtypes of CD90: CD90.1 and CD90.2. The difference between the two subtypes is due to allelic differences on the loci. CD90.1 and CD90.2 are expression variants controlled by different gene alleles. For example, in C57BL/6 mice, CD90.1 expression is regulated by the Ly5.2 locus, while CD90.2 is controlled by the Ly5.1 locus. Due to the differences in the loci of CD90.1 and CD90.2, these subtypes can be used for labeling in experiments to distinguish cells of different origin. By introducing the allele of CD90.1 or CD90.2, cells can be genetically labeled to identify, trace and quantitatively analyze cells of specific origin. CD90 can be expressed on hematopoietic stem cells, neurons, all thymic cells, and peripheral T cells. The mouse strains expressing CD90.1 included AKR, BDP, MA/MyJ, etc., and more mouse strains expressing CD90.2 included Balb/c, CBA/J, C3H/He, C57BL/-, DBA, NZB/-, etc.

CD45 is a receptor-type tyrosine phosphatase, also known as cluster of differentiation 45, that affects multiple signaling pathways, including T cell receptor (TCR) and B cell receptor (BCR) by regulating tyrosine phosphorylation levels. CD45 widely exists on the surface of hematopoietic cell membrane and is expressed on all leukocyte. Six isomers have been identified according to their extracellular epitopes, while CD45RA, CD45RB and CD45RO, have been identified on the surface of human cells. Then, two new subgroups of T cells can be identified by using this isomer molecule. CD45RA+ T cells are regarded as naive T cells (Tn) which means they are not stimulated by antigen , while CD45RO+ cells are known as memory T cells (Tm) been stimulated and differentiated by antigen.

CD62L, CD62E, and CD62P are two immune cell surface molecules that belong to the selectin family.
CD62L, also known as L-selectin, is a protein in the integrin family that is expressed primarily on the surface of white blood cells. It is involved in regulating the adhesion and migration of white blood cells, especially in inflammation and immune responses. By binding to its ligand, such as PECAM-1 on vascular endothelial cells, CD62L helps leukocyte to roll out of the circulation and migrate specifically to areas such as inflammation sites or lymph nodes.
CD62P, also known as P-selectin, is a adhesion molecule that is expressed primarily on endothelial cells and platelets. In the process of inflammation and thrombosis, CD62P on endothelial cells can be expressed rapidly and bind to ligands (such as PSGL-1) on white blood cells to promote mutual adhesion and activation of white blood cells and platelets.
CD62E, also known as E-selectin, is an adhesion molecule that is expressed primarily on endothelial cells.

The difference between these two antibodies is the clone number, which shows the particular cell line for screening antibody. Antibodies with same clonal number target exactly the same epitope. Both of these two antibodies are avaliable.

As a recommandation, F4/80 and CD11b are always used for identyfing macrophages of mouse, and CD86 and CD206 can be used for a further seperation for M1 abd M2 respectively. Specific indicators can be determined according to the literature and experimental requirements.

For the identification of mouse NK cells, CD3-CD49b+ or CD3-NK1.1+ should be selected according to the mouse strain, such as CD49b(DX5) for BALB/c mice and NK1.1 for C57BL/6 mice. CD49b is recommended for other strains.