CD27 Ligand, a type II transmembrane protein, is a member of the TNF superfamily. It is expressed on activated T and B lymphocytes as well as NK cells. CD27L and its receptor (CD27) regulate the immune response by promoting T-cell expansion and differentiation, as well as NK enhancement. CD27 signaling can act as a co-stimulatory effector to sustain the survival of CD8 T cells, primarily by inducing increased expression of the IL-2 gene. Full length human CD27L is a 193 amino acid protein, consisting of a 17 amino acid cytoplasmic domain, a 21 amino acid transmembrane domain, and a 155 amino acid extracellular domain. Human soluble CD27L corresponds to the 155 amino acid extracellular domain of the full length CD27L protein. PeproTech's recombinant human sCD27L contains the extracellular domain plus an N-terminal His-Tag.