Chemokinesis, chemotaxis, and chemotactic index (accuracy) in neutrophils from younger and older subjects toward CXCL8 (A,C,E) and sputum (B,D,F). Neutrophils from healthy subjects (aged <35 or >65 years of age) migrated toward CXCL8 (100 nM) or pooled sputum collected from patients admitted to the hospital with an acute lower respiratory tract infection attributable to S. pneumoniae. Measurements were taken from 10 randomly selected cells from each individual, with 10 subjects in each group. The average results for each subject were calculated, and an overall average was used for comparisons between groups. Bars represent the mean migratory parameter with SD shown as the error line (A-F). Chemokinesis and chemotaxis were measured in micrometers per minute. Accuracy is a measure of the cell’s directional orientation and is expressed in a cs ranging from −1 to 1. * indicates significant difference in migratory parameter from negative control data (P < .05); §, significant difference in migratory parameter between young and old samples.