The BC96 monoclonal antibody specifically reacts with the 55 kDa type I transmembrane glycoprotein known as the interleukin-2 receptor α (IL-2R α, also known as CD25). CD25 is expressed by the early progenitors of T and B lymphocytes lineage, and by activated mature T and B lymphocytes. CD25 is a low affinity interleukin-2 receptor, but its association with the IL-2 receptor β chain (CD122) and the common γ chain (CD 132) results in a high affinity IL-2R complex. CD25 plays an important role in B and T cell proliferation, differentiation, and activation.