The 114 monoclonal antibody specifically binds to mouse CD212 (the β1 subunit of IL-12Rβ1), originally termed IL-12Rβ, of the mouse IL-12 receptor complex. The IL-12Rβ1 subunit associates with a β2 subunit to form a heterodimeric IL-12 receptor complex. Each one of the IL-12R subunits exhibits low affinity for IL-12, but in combination, they bind IL-12 with high affinity. The IL-12Rβ1 subunit interacts primarily with IL-12 p40 whereas the IL-12Rβ2 binds both to IL-12 p40 and IL-12 p35. IL-12Rβ1 is required for high affinity binding of IL-12 but IL-12Rβ2 is required for signaling. IL-12Rβ1 has more recently been described to bind IL-23, a heterodimer formed of the p40 subunit from IL-12, and p19. The cytoplasmic regions of the β1 and β2 subunits contain the box1 and box2 motifs found in other cytokine receptors such as gp130, LIFR and G-CSFR. IL-12Rβ1 are primarily expressed by activated T cells and NK cells. Experiments with IL-12Rβ1 deficient mice have shown that IL-12Rβ1 is necessary for mouse T and NK cell responsiveness to IL-12 p75. The 114 antibody was generated by immunizing IL-12Rβ1 deficient mice of (129 x BALB/c)F1 background with mouse Ba/F3 cells that were stably transfected with IL-12Rβ1.