Molecular characterization of the mAb 8-301-defined antigen. (A) Lysates of CD45⁺ and CD45-deficient Jurkat cells were used in Western blots to validate the reactivity of mAb 8-301 with CD45 in parallel with the conventional CD45 mAb MEM-28. (B) Flow cytometric analysis revealed that mAb 8-301, in contrast to MEM-28, shows intracellular reactivity with monocytes. The figure shows histogram profiles including isotype-matched control mAb VIAP (open) and mAb 8-301 or MEM-28 (filled). (C) Reactivity of mAb 8-301 with cytoplasmic tails of protein tyrosine phosphatases CD45, RPTPγ, and LAR was tested by immunoblot (left). Loading was controlled by Ponceau S staining of the membrane (right). Representative experiments of at least 2 independent experiments are shown.