Incubation of polymorphonuclear leukocytes (PMN) with neuraminidase (Vibrio cholerae; 0.50 U/ml) resulted in release of 30% of the total amount of cell sialic acid. Neuraminidase-treated PMN phagocytized significantly more staphylococci opsonized in heated immune serum than control PMN (142 ± 18% vs 100 ± 5%; p < 0.001). No difference between phagocytosis of staphylococci opsonized in agammaglobulinemia serum by neuraminidase-treated PMN and control PMN was observed. Neuraminidase-treated PMN produced more superoxide upon stimulation by staphylococci opsonized in heated immune serum than control PMN (198 ± 19% vs 100 ± 10%; p < 0.001), but not after stimulation with staphylococci opsonized in agammaglobulinemia serum. Also, generation of chemiluminescence and the consumption of oxygen by neuraminidase-treated PMN was enhanced after stimulation by staphylococci opsonized in heated immune serum, but not by staphylococci opsonized in agammaglobulinemic serum. When phagocytosis and superoxide production were measured simultaneously and the amount of superoxide generated per phagocytized particle was determined, neuraminidase-treated PMN generated more superoxide per phagocytized particle than control PMN when the bacteria were opsonized in heated immune serum. Similar results were obtained when PMN were treated with influenza virus neuraminidase or when sialic acid was oxidized with NalO4 (1 mM; 15 min O°C). We conclude that partial removal of sialic acid enhances Fc-mediated phagocytosis, oxygen consumption, and superoxide production by PMN and that the increased production of superoxide is not only due to the enhanced phagocytosis.
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Henricks et al. (1982) studied this question.