About PD-1
Programmed cell death protein 1 (PDCD1) is an immune-inhibitory receptor expressed in activated T cells; it is involved in the regulation of T-cell functions, including those of effector CD8+ T cells. In addition, this protein can also promote the differentiation of CD4+ T cells into T regulatory cells. PDCD1 is expressed in many types of tumors including melanomas, and has demonstrated to play a role in anti-tumor immunity. Moreover, this protein has been shown to be involved in safeguarding against autoimmunity, however, it can also contribute to the inhibition of effective anti-tumor and anti-microbial immunity. [provided by RefSeq, Aug 2020]

About PE-eFluor 610
PE-eFluor™ 610 (PE-eF610, RPE-eF610) from Thermo Fisher Scientific is an orange-emitting tandem fluorophore that combines pycoerythrin (PE) and eFluor™ 610. The donor molecule, PE can be excited by the 488-nm blue, 532-nm green, or 561-nm yellow-green laser and and transfers energy to the acceptor molecule, eF610, which emitts light that can be captured with a 610/20 nm bandpass filter. PE-eF610 has an excitation peak at 565 nm and an emission peak at 607 nm, and is suitable alternative to PE-Texas Red®. PE-eF610 is mainly used for flow cytometry. This tandem is often a great option because of PE is excitable by multiple lasers due to its broad excitation spectrum and the eFluor™ 610 acceptor molecule emits brightly in the Orange/Red spectrum. Many cytometers are commonly set up with the 610/20 bandpass filter that can detect this fluorophore's emission. This dye is part of the larger eFluor™ dye family, developed by eBioscience which is now part of ThermoFisher Scientific.