This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services E-mail this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wei, Q. Articles by Fultz, P. N. Search for Related Content PubMed PubMed Citation Articles by Wei, Q. Articles by Fultz, P. N.

 Previous Article  |  Next Article 

Clinical and Vaccine Immunology, July 2006, p. 768-778, Vol. 13, No. 7
1071-412X/06/$08.00+0     doi:10.1128/CVI.00042-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Simian Immunodeficiency Virus (SIV)/Immunoglobulin G Immune Complexes in SIV-Infected Macaques Block Detection of CD16 but Not Cytolytic Activity of Natural Killer Cells

Qing Wei,¹ Jackie W. Stallworth,¹ Patricia J. Vance,² James A. Hoxie,² and Patricia N. Fultz^1*

Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294,¹ Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104²

Received 2 February 2006/ Returned for modification 6 March 2006/ Accepted 25 April 2006

Natural killer cells are components of the innate immune system that play an important role in eliminating viruses and malignant cells. Using simian immunodeficiency virus (SIV) infection of macaques as a model, flow cytometry revealed a gradual loss of CD16⁺ NK cell numbers that was associated with disease progression. Of note, the apparent loss of NK cells was detected in whole-blood samples but not in isolated peripheral blood mononuclear cells (PBMC), suggesting that an inhibitor(s) of the antibody used to detect CD16, the low-affinity immunoglobulin G (IgG) receptor, was present in blood but was removed during PBMC isolation. (Actual decreases in CD16⁺ cell numbers in PBMC generally were not detected until animals became lymphopenic.) The putative decrease in CD16⁺ cell numbers in whole blood correlated with increasing SIV-specific antibody titers and levels of plasma virion RNA. With the addition of increasing amounts of plasma from progressor, but not nonprogressor, macaques to PBMC from an uninfected animal, the apparent percentage of CD16⁺ cells and the mean fluorescence intensity of antibodies binding to CD16 declined proportionately. A similar decrease was observed with the addition of monomeric IgG (mIgG) and IgG immune complexes (IgG-ICs) purified from the inhibitory plasma samples; some of the ICs contained SIV p27^gag antigen and/or virions. Of interest, addition of purified IgG/IgG-ICs to NK cell lytic assays did not inhibit killing of K562 cells. These results indicate that during progressive SIV and, by inference, human immunodeficiency virus disease, CD16⁺ NK cell numbers can be underestimated, or the cells not detected at all, when one is using a whole-blood fluorescence-activated cell sorter assay and a fluorochrome-labeled antibody that can be blocked by mIgG or IgG-ICs. Although this blocking had no apparent effect on NK cell activity in vitro, the in vivo effects are unknown.

---

* Corresponding author. Mailing address: Department of Microbiology, University of Alabama at Birmingham, BBRB 509E, 845 19th Street South, Birmingham, AL 35294. Phone: (205) 934-0790. Fax: (205) 975-6788. E-mail: pnf{at}uab.edu.

---

Clinical and Vaccine Immunology, July 2006, p. 768-778, Vol. 13, No. 7
1071-412X/06/$08.00+0     doi:10.1128/CVI.00042-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Stratov, I., Chung, A., Kent, S. J. (2008). Robust NK Cell-Mediated Human Immunodeficiency Virus (HIV)-Specific Antibody-Dependent Responses in HIV-Infected Subjects. J. Virol. 82: 5450-5459 [Abstract] [Full Text]