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only induce the chemotaxis of NK cells but also induce the mobilization of
intracellular calcium in these cells (Loetscher et al., 1996). In addition, CC
chemokines induce granule exocytosis in NK cells ( Taub et al., 1995). The role
of chemokines in NK in HIV infection is worth studying.
NK cells produce cytokines (e.g., IFN-g and TNF-a) and the chemokine
macrophage in¯ammatory protein (MIP-1a) following stimulation with the
combination of two cytokines, IL-15 and IL-12. Monokine and activated
NK cells from normal or HIV
donors produce similar amounts of MIP-1a,
MIP-b, and RANTES protein in vitro. Because these chemokines are HIV-1-
suppressive factors, supernatants from monokine-activated NK cells inhibit
HIV replication in vitro. The chemokines are in part responsible for suppression,
and the other factors in the supernatants are implicated. These ®ndings suggest
the role for NK in the regulation of HIV-1 infection ( Fehniger et al., 1998).
CONCLUSION
The role of NK cells in the development and pathogenesis of HIV infection is
supported by several lines of evidence. It is also now recognized that NK cells
play a pivotal role in both innate immunity and the regulation of adaptive im-
munity. Thus, means to control the frequency, activity, and functions of NK
cells in HIV infection are of paramount importance in the prevention as well as
in the control of the progression of the disease. At present, the biology of NK
cell functions is rapidly being explored and many new developments have been
witnessed during the last years, such as the characterization and expression and
function of NK receptors and their role in signaling the cells for functional
activity. Further, new studies in the development of NK cells from precursor
cells and their di¨erentiation by various cytokines permits a better understand-
ing of the dynamics of NK cell-mediated di¨erentiation in infection. Therefore,
continuous investigations at both the fundamental and clinical levels of the role
of NK cells in HIV infection are needed for translation of the in vitro ®ndings
into the clinic to control HIV infection.
Acknowledgments. The author is grateful to the UCLA AIDS Institute for
support of the various studies performed in the ®eld of HIV infection. The
author acknowledges the assistance of Ms. Stephanie Louie in the preparation
of this manuscript.
REFERENCES
Abrams SI, Brahmi Z. 1988. Target cell directed NK inactivation. Concomitant loss of NK and
antibody-dependent cellular cytotoxicity activities. J Immunol 140: 2090±2095.
Allavena P, Bianchi G, Zhou D, van Damme J, Jilek P, Sozzani S, Mantovani A. 1994. Induction
of natural killer cell migration by monocyte chemotactic protein-1, -2 and -3. Eur J Immunol 24:
3233±3236.
