Alterations in peripheral blood neutrophil function are known to occur in patients with colitis and may have a role in precipitating nonspecific tissue injury. It is not known whether neutrophil function is altered in patients with Shigella dysenteriae type 1 infection, during which there is extensive colitis and which may be associated with life-threatening complications in young children. Three aspects of peripheral blood neutrophil function, polarization, attachment to yeast particles, and locomotion, were therefore studied in 111 children with S. dysenteriae type 1 infection and 57 children without any infection. All children were aged 12 to 60 months. Of the children with S. dysenteriae type 1 infection, 42 had leukemoid reaction, hemolytic-uremic syndrome, or septicemia (complicated shigellosis), while the others did not (uncomplicated shigellosis). Polarization and locomotion in the absence of chemoattractants and in response to N-formylmethionyl-leucylphenylalanine (FMLP) and the lipopolysaccharide (LPS) of S. dysenteriae type 1 were determined. Attachment to unopsonized and opsonized yeast particles was also determined. Children with shigellosis (uncomplicated or complicated) had more polarized neutrophils with and without chemoattractants than uninfected children (P < 0.05). Children with complicated shigellosis had more polarized neutrophils with FMLP at 10(-7) and 10(-6) M (P < 0.05) and with LPS than children with uncomplicated shigellosis (P < 0.05). At 3 to 5 days after enrollment, the numbers of polarized neutrophils with 10(-8), 10(-6), and 10(-5) M FMLP declined in children with uncomplicated shigellosis but not in those with complicated shigellosis. Attachment to yeast particles was similar in all three groups of children. Locomotion was inhibited by LPS in children with shigellosis (P < 0.05), whether it was uncomplicated or complicated, compared with locomotion in uninfected children. Finally, neutrophil polarization in uninfected children was negatively influenced by nutritional status. Thus, poorly nourished uninfected children had more polarized neutrophils with FMLP at 10(-9) M (P < = 0.02) and 10(-5) M (P = 0.043) than their better-nourished counterparts. In summary, altered neutrophil responses are associated with both uncomplicated and complicated shigellosis.