A 95-kDa fragment of CD45 is produced in monocytes and granulocytes. (A) Assessment of potential CD45 cleavage fragments with the intracellular-reactive CD45 mAb 8-301. B cells, T cells, monocytes (Mo), DCs, and granulocytes (Gr) were stimulated for different time periods with PMA, and lysates were analyzed by Western blot. A representative experiment of 3 independently performed is shown. (B) Membrane and cytoplasmic fractions of resting monocytes and of monocytes, stimulated for 3 hours with PMA, were isolated and analyzed in Western blots with mAb 8-301 for localization of the 95-kDa band. Isolation of membranes was controlled with a gp91^phox antibody, and isolation of cytoplasm was controlled with an actin antibody. One representative experiment of 2 independent experiments is shown. (C) MEM-28 does not react with the PMA-induced ct-CD45. A recombinant cytoplasmic CD45 protein covering the total intracellular part (lane 1), resting monocytes (lane 2), and monocytes stimulated for 90 minutes with PMA (lane 3) were analyzed in Western blots with mAb 8-301 and MEM-28.