The JM7A4 monoclonal antibody specifically binds to CD215, which is also known as the IL-15 Receptor alpha subunit (IL-15R-alpha, IL-15Ra, or IL-15Rα). This type I transmembrane glycoprotein is encoded by IL15RA (Interleukin 15 receptor subunit alpha) and is variably expressed on macrophages, natural killer (NK) cells, T cells and B cells and by some nonlymphoid cells including fibroblasts. Although it can independently bind IL-15 with high affinity, it does not contain a signaling motif. CD215 (IL-15Rα) can present IL-15 in cis or trans fashion to the IL-2/15R beta (CD122) and IL-2R gamma (γc or CD132) receptor complex which can then transduce signals intracellularly. Several different CD215 (IL-15Rα) isoforms have been described that are produced by alternative splicing and may alter signal transduction responses to IL-15. A cleaved soluble form of CD215 known as sIL-15RA has also been reported which can bind and antagonize IL-15 activity. By binding to its heterotrimeric receptor, IL-15 plays crucial roles in innate immunity, eg, through the activation of NK cells and adaptive immunity, eg, in enhancing the survival of CD8+ memory T cells.