Name: Flow Cytometry Antibody IgG4-APC, Clone SAG4
Antibody IgG4-APC is designed for flow cytometry use as a direct immunofluorescence reagent in the identification and enumeration of IgG4 expressing cells. IgG4-APC recognizes an epitope within Fc region (CH2 domain) of human IgG4.
IgG is the most abundant immunoglobulin in human serum (approximately 80% of total). Soluble IgG (sIgG) antibodies are distributed equally between the intra- and extravascular pools.
There are four different IgG subclasses responsible of protection against microorganisms: IgG1 (67% overall), IgG2 (22% overall), IgG3 (7% overall) and IgG4 (4% overall). These molecules have different biological properties as distinct ability to fix complement proteins and interact with phagocytic cell receptors. The IgG1 and IgG3 subclasses are particularly good opsonins and mediators of antibody dependent cell-mediated cytotoxicity (ADCC).
sIgG antibodies are important activators of complement but not as efficient as sIgM antibodies. IgG3 is the most efficient complement fixing IgG subclass, while IgG1 is somewhat less efficient, and IgG2 is even less so. IgG4 is unable to bind C1q and so cannot fix complement at all in the classical pathway.
Only IgG antibodies can cross the mammalian placenta, and maternal IgG1, IgG3, and IgG4 molecules have been found to be crucial for conferring the passive immunity that protects the developing human fetus and newborn in the first few months of life. IgG2 crosses the placenta with much lower efficiency.
CYT-IGG4AP should be used with BulkLysisTM (CYT-BL) buffer that allows you to stain a great number of cells and analyze low frequency subsets, as IgG4+ memory B cells and plasma cells. If another lysing protocol is used, two pre-staining washing steps using PBS + 1% (m/v) BSA + 0,09% (m/v) sodium azide must be performed.
This reagent must be used by flow cytometry qualified personnel.
Purified monoclonal anti-IgG4 antibody (mAb) conjugated with allophycocyanin (APC), supplied in phosphate buffered saline with 0,09% (m/v) sodium azide and BSA 1% (m/v).
- Clone: SAG4.
- Isotype: Mouse IgG1.
- Amount per vial: 25 tests using 3µL of mAb to 106 cells