Protein I, a translocatable ion channel from Neisseria gonorrhoeae, selectively inhibits exocytosis from human neutrophils without inhibiting O2- generation.

Protein I, the major outer membrane protein of Neisseria gonorrhoeae, is a voltage-dependent anion channel which can translocate from the gonococcus into human cells. Since granule exocytosis from neutrophils is regulated by ion fluxes, we examined the effect of protein I on neutrophil activation. Pretreatment with protein I (250 nM) impaired degranulation from neutrophils: beta-glucuronidase release decreased to 27 +/- 6% S.

Colchicine inhibits ionophore-induced formation of leukotriene B4 by human neutrophils: the role of microtubules.

Neutrophils which ingest particles (serum-treated zymosan, monosodium urate crystals) or are exposed to calcium ionophore A23187 generate leukotriene B4 (LTB4). Earlier work has shown that cells exposed to colchicine before exposure to monosodium urate crystals produce less LTB4; the formation of 5-HETE is unaffected. To determine whether inhibition by colchicine of LTB4 generation was stimulus-specific and was mediated by microtubule integrity, the effects of colchicine (10 microM, 60 min) on the release of lipoxygenase products from neutrophils exposed to ionophore A23187 (10 microM, 5 min) were examined.

Granules are necessary for death of neutrophils after phagocytosis of crystalline monosodium urate.

Crystalline monosodium urate (MSU) produces inflammation in vivo and kills phagocytes in vitro. A plausible hypothesis to account for crystal-induced cell death is that ingested crystals perforate the phagocytic vacuole into which lysosomes have degranulated: "lysis from within." However, it has also been contended that degranulation is not required for crystal-induced cell death.

Receptor-mediated entry of peroxidases into the parasitophorous vacuoles of macrophages infected with Leishmania Mexicana amazonensis.

Leishmania amastigotes, obligatory parasites of macrophages, lodge and multiply within long-lived phagolysosomelike "parasitophorous vacuoles" (PV). The glycoprotein horseradish peroxidase (HRP) was shown, by light and electron microscopic cytochemistry, to enter the PVs of rat in vitro-derived bone marrow macrophages infected with Leishmania mexicana amazonensis. Uptake was obtained both in preinfected macrophages incubated with HRP and in macrophages pulsed with HRP, infected, and further incubated in ligand-free medium.