APC-Cy5.5-conjugated anti-mouse antibodies are fluorescent immunoreagents that combine the red-laser-excited brightness of allophycocyanin (APC) with the far-red emission of the cyanine dye Cy5.5 through a fluorescence resonance energy transfer (FRET) tandem architecture. Because the laboratory mouse (Mus musculus) is the most widely used mammalian model organism, reagents enabling sensitive multicolor detection of mouse antigens are indispensable across immunology, hematology, stem cell biology, and cancer research.

Applications

APC-Cy5.5-conjugated anti-mouse antibodies are validated primarily for flow cytometry, with typical working volumes of 5 µL per test or 0.2 µg per 10⁶ cells. They are employed for immunophenotyping of mouse T cell subsets (CD3, CD4, CD8), B cell analysis (CD45R/B220), pan-leukocyte identification (CD45), and stem cell marker analysis. The far-red emission at approximately 695 nm minimizes spectral overlap with green (FITC) and orange (PE) fluorophores, facilitating multicolor panel design.

Advantages in Multicolor Flow Cytometry

APC-Cy5.5 offers several advantages for high-parameter flow cytometry panel design. It is efficiently excited by the 633–640 nm red laser line, which is standard on most modern benchtop flow cytometers. The far-red emission at approximately 695 nm occupies a detection channel between APC (660 nm) and APC-Cy7 (780 nm), enabling the construction of high-parameter panels with minimal spectral crowding in the red-laser-excited range. APC-Cy5.5 is particularly useful in panels where the APC channel is already occupied and the APC-Cy7 channel is needed for a dim antigen, as the APC-Cy5.5 channel provides an intermediate far-red option.