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Infect. Immun., 01 1995, 160-167, Vol 63, No. 1
R Bjerknes, HK Guttormsen, CO Solberg and LM Wetzler
Porins are trimeric proteins that constitute water-filled pores that allow
transmembrane diffusion of small solutes through the outer membrane layer
of gram-negative bacteria. The porins are capable of inserting into the
membranes of eucaryotic cells, and in the present study we have examined
the in vitro effects on neutrophil functions of the following purified
porins: meningococcal outer membrane protein classes 1 and 3 and gonococcal
outer membrane protein 1B (P1B). The neisserial porins inhibited human
neutrophil chemoattractant-induced actin polymerization and degranulation
of both primary and secondary granules. The neutrophil expression of
immunoglobulin G (IgG) Fc receptors II (Fc gamma RII; CDw32) and III (Fc
gamma RIII; CD16), as well as the activation-dependent downregulation of Fc
gamma RIII, were reduced by the meningococcal and gonococcal porins. The
neisserial porins impaired the upregulation of complement receptors 1
(CD35) and 3 (CD11b) and inhibited the phagocytic capacity of neutrophils,
as evaluated by the uptake of meningococci (strain 44/76) in the presence
of patient serum containing known amounts of IgG against meningococcal
porins. The porins also primed neutrophils to increase their intracellular
hydrogen peroxide production in response to FMLP, whereas no such priming
was observed if the neutrophil protein kinase C was stimulated directly
with phorbol myristate acetate. The neisserial porins influenced neutrophil
functions in a time- and concentration- dependent manner. The meningococcal
class 1 outer membrane protein and the gonococcal P1B tended to alter
neutrophil functions more than the meningococcal class 3 protein. Thus, the
neisserial porins inhibited human neutrophil actin polymerization,
degranulation, opsonin receptor expression, and phagocytosis but primed the
neutrophils to increase their oxidative burst. It remains to be determined
whether these in vitro observations reflect mechanisms that may be of
importance for the interaction between neutrophils and Neisseria species in
vivo.
Copyright © 1995, American Society for Microbiology
Neisserial porins inhibit human neutrophil actin polymerization, degranulation, opsonin receptor expression, and phagocytosis but prime the neutrophils to increase their oxidative burst
Department of Pediatrics, University of Bergen, Haukeland Hospital, Norway.
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