Competitive transplantation with wild-type and Gabpa KO cells. (A) Schematic representation of competitive bone marrow transplantation. Irradiated C57BL/6J KO recipient mice were infused with equal numbers of bone marrow cells from CD45.1⁺ wild-type donor mice and CD45.2⁺Gabpa^fl/fl-Mx1 Cre donor mice. Irradiated C57BL/6J control recipient mice were infused with equal numbers of bone marrow cells from CD45.1⁺ wild-type donor mice and CD45.2⁺Gabpa^fl/fl donor mice. Engraftment of both donor populations was examined 4 weeks later by flow cytometry of peripheral blood for CD45 isoforms. Both groups of recipient mice were injected with pIC 6 weeks after initial transplantation. (B) CD45.2⁺ cells were examined by flow cytometry for expression of CD11b and Gr1 at the indicated times. Sequential percentage values ± SEM of CD11b⁺ or Gr1⁺ cells in the CD45.2⁺ compartment are normalized to each mouse's values immediately before pIC injection. All findings from at least 3 independent biologic specimens. (C) Differential cell counts of bone marrow sorted for the indicated CD45 isoforms, from recipient control or recipient KO mice, presented as percentage from > 300 cell count.