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J. Virol., 01 1998, 286-293, Vol 72, No. 1
O Alsmadi and SA Tilley
The characteristics of antibody-dependent cellular cytotoxicity (ADCC)
directed by a panel of human and chimpanzee antienvelope (anti-Env)
monoclonal antibodies (MAbs) of different epitope specificities were
studied; this was accomplished by using target cells expressing human
immunodeficiency virus type 1 (HIV-1) Envs of either primary or
laboratory-adapted strains. Human MAbs of similar apparent affinities (1 x
10(9) to 2 x 10(9) liters/mol) against either a "cluster II"- overlapping
epitope of gp41 or against the CD4 binding site, V3 loop, or C5 domain of
gp120 directed substantial and comparable levels of specific lysis against
targets infected with laboratory-adapted strains of HIV-1. As expected,
those MAbs specific for relatively conserved regions of Env generally
exhibited ADCC activity against a broader range of HIV-1 strains than those
directed against variable epitopes. Significant ADCC activities of selected
MAbs against primary isolate Env-expressing cells were demonstrated. In
addition, a new ADCC epitope in the V2 domain of gp120 was defined. CD56+
cells were demonstrated to be the effector cells in these studies by
fluorescence-activated cell sorting followed by ADCC assays. Notably, all
anti-Env MAbs tested in this study, including MAbs directed against each of
the known neutralization epitope clusters in gp120, directed significant
levels of ADCC against targets expressing Env of one or more HIV-1 strains.
These results imply that many, if not most, HIV-1-neutralizing human Abs of
high affinity (> or = 3 x 10(8) liters/mol in these studies) and of the
immunoglobulin G1 (IgG1) subclass (i.e., the predominate IgG subclass) are
capable of directing ADCC. Since neutralizing Abs have been associated with
long-term survival following HIV-1 infection, this suggests that ADCC
activity may be beneficial in vivo.
Copyright © 1998, American Society for Microbiology
Antibody-dependent cellular cytotoxicity directed against cells expressing human immunodeficiency virus type 1 envelope of primary or laboratory-adapted strains by human and chimpanzee monoclonal antibodies of different epitope specificities
Public Health Research Institute, New York, New York 10016, USA.
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