Bone marrow progenitor populations, frequency of blood eosinophils, and lung tissue eosinophil numbers in wt and CD34^−/− mice. (A) Frequency of bone marrow hematopoietic progenitor markers in OVA-challenged mice. (Ai) B220⁺ indicates B lymphocytes; c-kit⁺, immature progenitors; Gr1⁺, granulocytes; Mac-1⁺, monocytes; and Ter-119⁺, erythroid; (Aii) Lin⁻Sca⁻IL5R⁺ indicates eosinophil progenitors; and CD3⁺, T lymphocytes. All cells were analyzed by FACS (n=4; error bars represent SEM for each marker). (B) Frequency of blood CD45⁺/CCR3⁺ cells (eosinophils) in naive and OVA-challenged wt and CD34^−/− mice (n=6; *P=.02; error bars=SEM). (C) Frequency of CD45⁺/CCR3⁺ cells in hematopoietic-cell preparations from individual lungs of naive and OVA-challenged wt and CD34^−/− mice was analyzed by FACS. Total hematopoietic cells/lung counts were obtained and used to determine total eosinophils/lung. (n=4; *P=.01; error bars=SEM).