Product details
Synonyms = Fc fragment of IgG receptor IIb,CD32,CD32B,FCG2,FCGR2,FCGR2C,FcRII-c,IGFR2
Antibody type = Recombinant Rabbit monoclonal / IgG
Clone = HMV315
Positive control = Liver: A moderate to strong CD32B positivity of sinusoidal endothelial cells should be seen.
Negative control = Colon: Epithelial cells must be CD32B negative.
Cellular localization = Membraneous
Reactivity = Human
Application = Immunohistochemistry
Dilution = 1:100 – 1:200
Intended Use = Research Use Only
Relevance of Antibody
CD32B is an inhibitory Fc gamma receptor.
Biology Behind
CD32B also termed FcγRIIB is an 40 kDa glycoprotein coded by the FCGR2B gene on chromosome 1q23.3. CD32B is a type I transmembrane receptor with low affinity for monomeric IgG. CD32B is the only known inhibitory Fc gamma receptor. It is expressed on subsets of lymphocytes, dendritic cells, and endothelial cells. CD32B reduces downstream signaling of co-localized activating receptors following ligand-induced crosslinking. CD32B is known as a critical regulatory element in B-cell homeostasis as it controls cell activation by counterbalancing the stimulatory activity of multiple receptors, including the B-cell antigen receptor (BCR). It down-regulates B cell activation by increasing the threshold for BCR activation and suppresses B cell-mediated Ag presentation to T cells. CD32B is of considerable therapeutic interest. On normal and malignant B cells, CD32B can play a role in internalizing the anti-CD20 antibody drug rituximab from the B cell surface which results in an abrogation of its cell-mediated anticancer mechanisms. Moreover, CD32B is involved in adaptation to all kinds of intravenous Ig treatments, and it can potentiate the immunostimulatory activities of certain therapeutic mAbs targeting TNFR family members. Therapeutic antibodies directly targeting CD32B are also under development.
Suggested reading: https://jlb.onlinelibrary.wiley.com/doi/full/10.1002/jlb.2mir0917-354r.
Staining Pattern in Normal Tissues
Images describing the CD32B staining pattern in normal tissues obtained by the antibody HMV315 are shown in our “Normal Tissue Gallery”.
| Brain | Cerebrum | Negative. |
| Cerebellum | Negative. | |
| Endocrine Tissues | Thyroid | Negative*. |
| Parathyroid | Negative*. | |
| Adrenal gland | Negative*. Distinct CD38B positivity of monocytic cells. | |
| Pituitary gland | Distinct CD38B staining of some (monocytic and/or endothelial) cells, especially in the posterior lobe. | |
| Respiratory system | Respiratory epithelium | Negative*. |
| Lung | Negative*. | |
| Gastrointestinal Tract | Salivary glands | Negative*. |
| Esophagus | Negative*. | |
| Stomach | Negative*. | |
| Duodenum | Negative*. | |
| Small intestine | Negative*. | |
| Appendix | Negative*. | |
| Colon | Negative*. | |
| Rectum | Negative*. | |
| Liver | Moderate to strong CD38 staining of sinusoidal endothelium. | |
| Gallbladder | Negative*. | |
| Pancreas | Negative*. | |
| Genitourinary | Kidney | Negative*. CD38B staining of some monocytic cells and perhaps also of some endothelial cells of some microvessels. |
| Urothelium | Negative*. | |
| Male genital | Prostate | Negative*. |
| Seminal vesicles | Negative*. | |
| Testis | Negative*. CD32B positivity occurs in microvessel endothelium. | |
| Epididymis | Negative*. CD32B positivity occurs in microvessel endothelium. | |
| Female genital | Breast | Negative*. |
| Uterus, myometrium | Negative*. | |
| Uterus, ectocervix | Negative*. | |
| Uterus endocervix | Negative*. | |
| Uterus, endometrium | Negative*. | |
| Fallopian Tube | Negative*. | |
| Ovary | Negative*. | |
| Placenta early | Strong CD32B positivity of all endothelial cells. | |
| Placenta mature | Strong CD32B positivity of all endothelial cells. | |
| Amnion | Negative*. | |
| Chorion | Negative*. | |
| Skin | Epidermis | Negative*. Distinct CD32B positivity of intraepidermal Langerhans cells. |
| Sebaceous glands | Negative*. | |
| Muscle/connective tissue | Heart muscle | Negative*. |
| Skeletal muscle | Negative*. Strong CD38B staining of a fraction (not of all!) of endothelial cells in small vessels. | |
| Smooth muscle | Negative*. | |
| Vessel walls | Endothelial cells of microvessels can be positive (only in selected tissue types). | |
| Fat | Negative*. | |
| Stroma | CD38B positivity occurs mainly in monocytic cells, B-lymphocytes, and may also be seen in the endothelium of microvessels (only in selected tissue types). Endothelial positivity is often difficult to discern from CD32B positive monocytic cell types. | |
| Endothelium | Endothelial cells of microvessels can stain CD32B positive in selected tissue types. | |
| Bone marrow/ lymphoid tissue | Bone marrow | CD38B staining of a significant fraction of cells. |
| Lymph node | CD38B staining of variable intensity in a large fraction of B-lymphocytes and perhaps also other cells. CD32B staining is least intense in most germinal centre cells. | |
| Spleen | CD38B staining of variable intensity in most B-lymphocytes of the white pulpa. | |
| Thymus | CD38B staining of only few cells. | |
| Tonsil | CD38B staining of variable intensity in a large fraction of B-lymphocytes and perhaps also other cells. CD32B staining is least intense in most germinal centre cells. | |
| Remarks | *CD38B positivity of a fraction of inflammatory cells occurs in all tissues. In some tissues, CD32B positivity can also be seen in endothelia of microvessels. Endothelial positivity is often difficult to discern from CD32B positive monocytic cell types. |
RNA and protein expression data of CD32B findings are also described in the Human Protein Atlas (Tissue expression CD32B).
Positive control = Liver: A moderate to strong CD32B positivity of sinusoidal endothelial cells should be seen.
Negative control = Colon: Epithelial cells must be CD32B negative.
Staining Pattern in Relevant Tumor Types
A positive CD32B immunostaining can be seen in tumor cells of many B-cell Non-Hodgkin’s lymphomas. Variable numbers of CD32B positive non-neoplastic lymphocytes and monocytic cells can be seen in most cancers.
The TCGA findings on CD32B RNA expression in different tumor categories have been summarized in the Human Protein Atlas.
Compatibility of Antibodies
No data available at the moment
Protocol Recommendations
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 HMV315 at a dilution of 1:200 at 37°C for 60 minutes. Visualization of bound antibody by the EnVision Kit (Dako, Agilent) according to the manufacturer’s directions.
Potential Research Applications
- CD32B is being evaluated as a drug target protein for B-cell Non-Hodgkin’s lymphoma and for immune response modulation.
- The role of CD32B in intravenous Ig therapy is substantial and not sufficiently clarified.
- Numerous CD32B agonists and antagonists are under development and are being evaluated for clinical utility.
Evidence for Antibody Specificity in IHC
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 HMV315 specificity is suggested by the good 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 CD32B). In agreement with HMV315 immunostaining data, RNA expression strongly predominated in the placenta while CD32B RNA was also described to occur at significant levels in other organs with significant quantities of CD32B positive cells (liver, tonsil, lymph node, spleen).
Comparison of antibodies: True expression of CD32B in all cell types with CD32B positivity by HMV315 is corroborated by an identical staining obtained by a commercially available independent second antibody (termed “validation antibody”).
Independence of the validation antibody is demonstrated by various additional stainings (smooth muscle, heart muscle, various epithelial cell types) that were only seen by using the validation antibody and not by HMV315. These additional stainings that occurred after using the validation antibody were considered antibody specific cross-reactivities of the validation antibody.
