CBLB and Increased total leukocyte count: BM transplants (CD45.2+ donor to CD45.1+ lethally-irradiated syngeneic recipients) confirmed that DKO BM but not the Cbl-KO, Cbl-b-KO or Cre Control BM transplant produced leukocytosis and myelomonocytosis (Figure 1A) with rapid-onset lethality (Figure 1B) in recipients assessed at 4 weeks post-transplant.