Frequencies of myeloid and erythroid cell populations in blood and bone marrow of Btk-deficient mice. Blood (A-B) from wild-type (wt) and Btk-deficient mice (Btk-ko) were analyzed using an Animal Blood Counter for differential white blood cell (WBC) counts. Frequencies (A) and cell numbers per volume (B) of lymphocytes, neutrophilic granulocytes, and monocytes are shown. (C) Whole bone marrow (WBM) cells of femurs of wild-type and Btk-ko mice were stained for the expression analysis of surface markers CD11b (myeloid cells), Ter119 (erythrocytes), and B220 (lymphocytes). (D) The myeloid compartment was further analyzed by the expression of CD11b⁺Gr-1⁺ (granulocytes) and CD11b⁺Gr-1⁻ (monocytes). The frequency of cell populations was recalculated for defined cell numbers per femur (E-F). Data presented are the mean values (± SD). *P ≤ 0.05; ***P ≤ 0.0005. n represents the number of biological replicates.