Characteristics of bone marrow cells of patients with eosinophilic pneumonia

Bone marrow features were studied to clarify the pathogenesis of peripheral blood eosinophilia in eosinophilic pneumonia. We observed (1) increases in the number of nucleated cells in patients with this disease as compared with that of control subjects (205,944 +/- 104,253 versus 118,154 +/- 76,306) (P < .05); (2) increases in the myelocyte to erythrocyte ratio (6.95 +/- 4.06 versus 4.02 +/- 1.36) (P < .05) mainly due to a marked increase in the eosinophilic series; and (3) an increase in the eosinophilic series with advance in the maturation process, the degree of increase becoming greater with the increase in eosinophilic maturation. These findings suggest that differentiation and maturation of the precursor cells into mature eosinophils were accelerated in the bone marrow in eosinophilic pneumonia by some lymphokines as eosinophilopoietic growth factors.