Neutrophil numbers are maintained, both in the periphery and as progenitors in the bone marrow31; however, older adults are more prone to neutropenia during infection as response to G-CSF appears blunted.32 Some studies suggest that neutrophils from older adults display altered cytokine production, but there is inconsistency as to whether this manifests as decreased or increased proinflammatory cytokines, and this might be stimuli specific. The gene discussed is CSF3; the disease is infection.