Neutrophils chemotaxis. Cell migration distances (in mm) are measured microscopically in the direction of the chemoattractant (directed migration (DM)) and towards the control (spontaneous migration (SM)). Neutrophils chemotaxis index is expressed as the ratio of directed to spontaneous migration of PMN cells. x ± SEM; n = 20 subjects per group. Two-way repeated-measures ANOVA was performed to discriminate among the effects of age (A; p < 0.05), nutritional treatment (N; p < 0.05) and their interaction (I; p < 0.05). There was a significant effect of nutritional treatment for both chemotaxis index and spontaneous migration.