reactive neutrophilic pathogenesis clinical findings infection inflammation malignancy drugs emotional stimuli stress smoking hyposplenism asplenia rheumatoid arthritis Crohn’s epinephrine retinoic acid glucocorticoids anxiety exercise heat stroke surgery neutrophils neutrophil bone marrow demarginalization splenic sequestration neutrophilic ANC peripheral blood smear absolute neutrophil count left shift bands metamyelocytes myelocytes toxic granulations dohle bodies brenneis Siddique savoie ryznar