Allophycocyanin (APC)-conjugated anti-horse primary antibodies are far-red fluorescent immunoreagents optimized for flow cytometric applications requiring red laser excitation. Produced by immunizing hosts such as goat or rabbit with purified horse immunoglobulins, these antibodies are affinity-purified and conjugated to APC, a 105 kDa phycobiliprotein derived from cyanobacteria with excitation and emission maxima of 650 nm and 660 nm, respectively. APC exhibits exceptional brightness, with a high molar extinction coefficient (≈ 7.0 × 105 M−1cm−1) and a quantum yield of approximately 0.68, enabling sensitive detection of equine antigens expressed at very low densities. Its far-red emission minimizes spectral overlap with FITC and PE, making APC particularly suitable for multicolor immunophenotyping panels. Available specificities include anti-IgG (H+L), anti-IgG subclass, and anti-IgM reagents. Pre-adsorption against mouse, rat, rabbit, and human immunoglobulins further reduces cross-reactivity in multi-species experimental samples.
Applications
APC-conjugated anti-horse antibodies are widely used in flow cytometry and fluorescence-activated cell sorting (FACS), where their high fluorescence intensity and compatibility with 633–647 nm red lasers enable quantitative immunophenotyping of equine leukocyte populations and sensitive detection of intracellular cytokines. In multiplex bead-based assays, APC functions as a reporter fluorophore for the quantification of cytokines and other biomarkers. These conjugates are also employed in immunofluorescence microscopy and high-content imaging for antigen localization in fixed cells. The far-red emission spectrum helps reduce tissue autofluorescence, thereby improving signal-to-background ratios. Typical working dilutions for flow cytometry range from 1:50 to 1:500. These reagents are intended for research use only and are not approved for diagnostic procedures.