Neutrophils do not bind to or phagocytize human immune complexes formed
with influenza virus
DR Ratcliffe, J Michl and EB Cramer
Department of Anatomy, State University of New York Health Science Center,
Brooklyn 11203.
Neutrophils appear to form the first line of defense against influenza
virus, yet it is unclear how these leukocytes recognize influenza- infected
cells. While demonstrating that neutrophils adhere specifically to the
sialic acid-binding site on the hemagglutinin molecule (HA) on the surface
of influenza-infected (WSN[H1N1]) epithelial cells and not to other viral
or epithelial cell antigens, it was observed that human neutrophils do not
recognize immune complexes formed with influenza virus. Intact antibodies
(mouse monoclonal antibodies [MoAbs] IgG1 and IgG2b, human immune
heat-inactivated serum [predominantly IgG1], and IgG purified from human
immune serum) that block the sialic acid-binding site on HA significantly
reduced (> 80%) neutrophil adherence to influenza-infected epithelial
cells. Binding and phagocytosis of free influenza virions and neutrophil
agglutination by influenza virus were completely prevented by these
antibodies. Intact and F(ab')2 fragments of mouse MoAbs to other viral
epitopes caused increased neutrophil adherence to infected cells. This
binding was eliminated by F(ab'2) fragments of MoAbs against the sialic
acid- binding site on HA, but not by saturating amounts of MoAbs, which
block the neutrophil Fc receptors. Thus, it appears that human neutrophils
show little ability to bind via their Fc receptors to the immune complexes
formed with antibody and either influenza-infected epithelial cells or the
free virion. These findings are in contrast to the general dogma, and are
the first example of antibody opsonization reducing, rather than enhancing,
neutrophil binding and phagocytosis of a pathogen.
Volume 82,
Issue 5,
pp. 1639-1646,
09/01/1993
Copyright © 1993 by The American Society of Hematology
