Phycoerythrin (PE)-conjugated anti-mouse primary antibodies are immunoreagents that combine an antibody specific for a mouse antigen or immunoglobulin with phycoerythrin, a bright, orange-red fluorescent protein derived from cyanobacteria and red algae. PE is efficiently excited by a 488 nm blue laser or a 561 nm yellow-green laser and emits fluorescence at approximately 575 nm. These conjugated antibodies enable direct, one-step detection of target antigens, eliminating the need for secondary detection reagents. PE is one of the brightest commonly used fluorochromes, offering excellent signal-to-noise ratios and making it suitable for detecting low-abundance targets.

Applications

These reagents are used primarily in flow cytometry for immunophenotyping, rare-event analysis, and multicolor panels alongside fluorophores such as FITC, APC, and Pacific Blue. They can also be used in fluorescence microscopy and ELISA, depending on the assay format. PE performs well in cell-surface staining, although its relatively large molecular size may limit tissue penetration in microscopy. Fixation and permeabilization can affect fluorescence, so experimental conditions should be optimized for the intended application.

Specificity and Experimental Considerations

Specificity is determined by the antibody component. Monoclonal antibodies recognize a single epitope, whereas polyclonal antibodies recognize multiple epitopes on the same antigen. Cross-adsorption can help minimize cross-species reactivity. Antibody conjugation may slightly alter binding characteristics or fluorescence intensity because of steric effects. Appropriate controls, including isotype controls, unstained controls, and compensation controls for multicolor flow cytometry, are essential for reliable interpretation. PE is susceptible to photobleaching; therefore, reagents should be stored protected from light, and repeated freeze-thaw cycles should be avoided. Each lot should be validated for the intended application to support reproducible, target-specific detection.