CD171 (MSVA-171R)

The cell adhesion molecule L1 (CD171; L1CAM) is a multidomain membrane Typ 1 glycoprotein of the immunoglobulin superfamily coded by the L1CAM gene at chromosome Xq28. It plays a role in the development of the nervous system, by regulation of cell migration, adhesion, neuronal differentiation, myelination, and axon growth. L1 protein is located all over the nervous system on the surface of neurons. It is placed along the cellular membrane so that one end of the protein remains inside the nerve cell while the other end stays on the outer surface of the neuron. This position allows the protein to activate chemical signals which spread through the neuron. L1CAM has also been proposed as a marker of Extracellular Vesicles (EVs) originating from neuronal cells. Mutations in the L1 protein are the cause of L1 syndrome, characterized by corpus callosum hypoplasia, retardation, aphasia, spastic paraplegia and hydrocephalus). L1CAM protein expression also occurs in various types of tumors where it has been associated with tumor progression, metastasis, therapy resistance, stemness, and dismal outcome. L1CAM protein is currently evaluated as a therapeutic target by neutralizing antibodies, radioimmunoconjugates or chimeric antigen receptor-redirected T (CAR-T) cells.

L1CAM expression predominantly occurs in nerve fibres but it is also seen in few epithelial tissue types.  Images describing the CD171 staining pattern in normal tissues obtained by the antibody MSVA-171R are shown in our “Normal Tissue Gallery”.

MCM2 is a ubiquitously expressed protein. The findings described above are thus consistent with the RNA data described in the Human Protein Atlas (Tissue expression CD171). L1CAM expression predominantly occurs in nerve fibres but it is also seen in few epithelial tissue types.

Positive control = Kidney: A strong membranous L1CAM staining should be seen in a subset of collecting ducts while the vast majority of tubuli remains L1CAM negative.

Negative control = Kidney: L1CAM staining must be absent in the vast majority of tubuli (L1CAM staining is limited to collecting ducts).

Normal tissue gallery

Cancer tissue gallery

No data available at the moment

IHC users have different preferences on how the stains should look like. Some prefer high staining intensity of the target stain and even accept some background. Others favor absolute specificity and lighter target stains. Factors that invariably lead to more intense staining include higher concentration of the antibody and visualization tools, longer incubation time, higher temperature during incubation, higher temperature and longer duration of the heat induced epitope retrieval (slide pretreatment). The impact of the pH during slide pretreatment has variable effects and depends on the antibody and the target protein.

All images and data shown here and in our image galleries are obtained by the manual protocol described below. Other protocols resulting in equivalent staining are described as well.

Manual protocol

Freshly cut sections should be used (less than 10 days between cutting and staining). Heat-induced antigen retrieval for 5 minutes in an autoclave at 121°C in pH 7,8 Target Retrieval Solution buffer. Apply MSVA-171R at a dilution of 1:100 at 37°C for 60 minutes. Visualization of bound antibody by the EnVision Kit (Dako, Agilent) according to the manufacturer’s directions.

• The clinical utility of a potential prognostic role of L1CAM expression needs to be further evaluated.
• The utility of L1CAM is a potential therapeutic target that needs to be further investigated.
• The diagnostic role of L1CAM IHC is not clear.

There are two ways how the specificity of antibodies can be documented for immunohistochemistry on formalin fixed tissues. These are: 1. Comparison with a second independent method for target expression measurement across a large number of different tissue types (orthogonal strategy), and 2. Comparison with one or several independent antibodies for the same target and showing that all positive staining results are also seen with other antibodies for the same target (independent antibody strategy). 

Orthogonal validation: For the antibody MSVA-171R specificity is suggested by the strong concordance of the immunostaining data with data from three independent RNA screening studies, including the Human Protein Atlas (HPA) RNA-seq tissue dataset, the FANTOM5 project, and the Genotype-Tissue Expression (GTEx) project, which are all summarized in the Human Protein Atlas (Tissue expression CD171). L1CAM positivity by MSVA-171R is detectable in all tissues with documented L1CAM RNA expression (adrenal gland, pituitary gland, prostate, kidney, seminal vesicles, gastrointestinal tract). The only tissue without previously documented significant L1CAM RNA expression but L1CAM positivity by MSVA-171R (fallopian tube) had only very few positive cells that were probably not detected in RNA studies analyzing entire organs.

Comparison of antibodies: True expression of L1CAM in all cell types found L1CAM positive by MSVA-171R is further corroborated by identical stainings obtained by another commercially available independent antibody (termed “validation antibody”). This validation also confirmed positivity of a subset of epithelial cells in the fallopian tube.

Normal tissue gallery