2A12

2a12 is a murine monoclonal antibody clone that targets the surface protein CD52, a glycoprotein expressed on mature lymphocytes. The clone was first produced in 1986 by a hybridoma screen of BALB/c mice immunized with purified human CD52 protein. Because of its high affinity and specificity, 2a12 has become a cornerstone reagent in studies of T- and B-cell biology, as well as a tool for dissecting the role of CD52 in immune regulation.

In research contexts, 2a12 is routinely used in flow cytometry to identify CD52‑positive populations. It is also employed in immunoprecipitation and Western blotting assays to confirm protein expression in cell lines such as Ramos and Jurkat. Importantly, the clone has been immortalized to generate a stable production line for industrial supply, ensuring consistent epitope recognition and minimal lot-to-lot variability.

The epitope recognized by 2a12 lies within the N‑terminal carbohydrate‑modified region of CD52, a motif that remains conserved across mammalian species. Consequently, the antibody cross‑reacts with mouse, rat, and rabbit CD52, facilitating comparative immunological studies. However, due to the low glycosylation levels in some species, 2a12’s signal intensity can be reduced, necessitating optimization of fixation and permeabilization protocols.

Commercial vendors routinely offer 2a12 conjugated to fluorochromes such as FITC, PE, and APC, enabling multiplex panels in high‑dimensional flow cytometry. The clone’s documented binding kinetics (K_d ≈ 0.5 nM) render it suitable for both qualitative staining and quantitative cell sorting applications.