Actinobacillus actinomycetemcomitans suppresses rat natural killer cell activity in vivo

Mamdooh Ghoneum, Reinaldo Saglie, Jimmy J Brown, Christopher Regala

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Objective - To examine the immune suppressive effect of Actinobacillus actinomycetemcomitans (Aa) on rat natural killer (NK) cell activity in vivo. Material and Methods - Sprague-Dawley rats were given Aa in 2 different manners: (i) by mixing Aa with food at a dose of 108 cells/rat/day for 3 months; or (ii) by a single i.m. injection of live Aa at doses of 106 and 107 cells/rat/day. NK cell activity was measured by means of a 51Cr-release assay using YAC-1 tumor cells as targets. Results - Rats that had been infected by Aa mixed with food experienced significant suppression of their NK cell activity; this reached ≈ 50% of control values at 2 and 3 months post-Aa infection. The suppression in NK cell activity was related to decreases in the extent of conjugate formation between effectors and YAC-1 target tumor cells (51.7%) and the extent of lysis of target cells (75.7%). The results also showed that addition of an admixture of Aa-treated NK cells to the control NK cells caused 75% and 53% decreases in activity at effector:target ratios of 25:1 and 50:1, respectively. In addition, a significant increase in the extent of T-suppressor cells (154.8% of control) was detected at 3 months post-Aa infection. In contrast, the single injection of live bacteria resulted in a remarkable, dose-dependent inhibition of NK cell activity (55% and 71% at doses of 106 and 107 cells/rat/day, respectively) as early as 2 days post-treatment. This also reflected significant suppression in the effector:target conjugate formation ratio (52% of control). The data also revealed a 150-188% increase in the number of splenic lymphocytes post-Aa injection. These effects were transient and normal levels were re-established by the fifth day. Conclusion - Aa treatment causes suppression of NK cell activity and the mode of action may be due to induction of T-suppressor cells or dilution of NK cells with other lymphoid cell populations. The degree of suppression is affected by the way in which Aa is introduced to the host. These results may contribute to the understanding of how Aa evades host defense.

Original languageEnglish (US)
Pages (from-to)621-627
Number of pages7
JournalActa Oto-Laryngologica
Volume124
Issue number5
DOIs
StatePublished - Jul 14 2004

Fingerprint

Aggregatibacter actinomycetemcomitans
Natural Killer Cells
Actinobacillus Infections
Injections
Food
Lymphocyte Count
Sprague Dawley Rats
Neoplasms

Keywords

  • Bacterial infection
  • Immune suppression
  • Lymphocytes

ASJC Scopus subject areas

  • Otorhinolaryngology

Cite this

Actinobacillus actinomycetemcomitans suppresses rat natural killer cell activity in vivo. / Ghoneum, Mamdooh; Saglie, Reinaldo; Brown, Jimmy J; Regala, Christopher.

In: Acta Oto-Laryngologica, Vol. 124, No. 5, 14.07.2004, p. 621-627.

Research output: Contribution to journalArticle

Ghoneum, Mamdooh ; Saglie, Reinaldo ; Brown, Jimmy J ; Regala, Christopher. / Actinobacillus actinomycetemcomitans suppresses rat natural killer cell activity in vivo. In: Acta Oto-Laryngologica. 2004 ; Vol. 124, No. 5. pp. 621-627.
@article{60140134c903487392f8a8ed6d89eec4,
title = "Actinobacillus actinomycetemcomitans suppresses rat natural killer cell activity in vivo",
abstract = "Objective - To examine the immune suppressive effect of Actinobacillus actinomycetemcomitans (Aa) on rat natural killer (NK) cell activity in vivo. Material and Methods - Sprague-Dawley rats were given Aa in 2 different manners: (i) by mixing Aa with food at a dose of 108 cells/rat/day for 3 months; or (ii) by a single i.m. injection of live Aa at doses of 106 and 107 cells/rat/day. NK cell activity was measured by means of a 51Cr-release assay using YAC-1 tumor cells as targets. Results - Rats that had been infected by Aa mixed with food experienced significant suppression of their NK cell activity; this reached ≈ 50{\%} of control values at 2 and 3 months post-Aa infection. The suppression in NK cell activity was related to decreases in the extent of conjugate formation between effectors and YAC-1 target tumor cells (51.7{\%}) and the extent of lysis of target cells (75.7{\%}). The results also showed that addition of an admixture of Aa-treated NK cells to the control NK cells caused 75{\%} and 53{\%} decreases in activity at effector:target ratios of 25:1 and 50:1, respectively. In addition, a significant increase in the extent of T-suppressor cells (154.8{\%} of control) was detected at 3 months post-Aa infection. In contrast, the single injection of live bacteria resulted in a remarkable, dose-dependent inhibition of NK cell activity (55{\%} and 71{\%} at doses of 106 and 107 cells/rat/day, respectively) as early as 2 days post-treatment. This also reflected significant suppression in the effector:target conjugate formation ratio (52{\%} of control). The data also revealed a 150-188{\%} increase in the number of splenic lymphocytes post-Aa injection. These effects were transient and normal levels were re-established by the fifth day. Conclusion - Aa treatment causes suppression of NK cell activity and the mode of action may be due to induction of T-suppressor cells or dilution of NK cells with other lymphoid cell populations. The degree of suppression is affected by the way in which Aa is introduced to the host. These results may contribute to the understanding of how Aa evades host defense.",
keywords = "Bacterial infection, Immune suppression, Lymphocytes",
author = "Mamdooh Ghoneum and Reinaldo Saglie and Brown, {Jimmy J} and Christopher Regala",
year = "2004",
month = "7",
day = "14",
doi = "10.1080/00016480310015759",
language = "English (US)",
volume = "124",
pages = "621--627",
journal = "Acta Oto-Laryngologica",
issn = "0001-6489",
publisher = "Informa Healthcare",
number = "5",

}

TY - JOUR

T1 - Actinobacillus actinomycetemcomitans suppresses rat natural killer cell activity in vivo

AU - Ghoneum, Mamdooh

AU - Saglie, Reinaldo

AU - Brown, Jimmy J

AU - Regala, Christopher

PY - 2004/7/14

Y1 - 2004/7/14

N2 - Objective - To examine the immune suppressive effect of Actinobacillus actinomycetemcomitans (Aa) on rat natural killer (NK) cell activity in vivo. Material and Methods - Sprague-Dawley rats were given Aa in 2 different manners: (i) by mixing Aa with food at a dose of 108 cells/rat/day for 3 months; or (ii) by a single i.m. injection of live Aa at doses of 106 and 107 cells/rat/day. NK cell activity was measured by means of a 51Cr-release assay using YAC-1 tumor cells as targets. Results - Rats that had been infected by Aa mixed with food experienced significant suppression of their NK cell activity; this reached ≈ 50% of control values at 2 and 3 months post-Aa infection. The suppression in NK cell activity was related to decreases in the extent of conjugate formation between effectors and YAC-1 target tumor cells (51.7%) and the extent of lysis of target cells (75.7%). The results also showed that addition of an admixture of Aa-treated NK cells to the control NK cells caused 75% and 53% decreases in activity at effector:target ratios of 25:1 and 50:1, respectively. In addition, a significant increase in the extent of T-suppressor cells (154.8% of control) was detected at 3 months post-Aa infection. In contrast, the single injection of live bacteria resulted in a remarkable, dose-dependent inhibition of NK cell activity (55% and 71% at doses of 106 and 107 cells/rat/day, respectively) as early as 2 days post-treatment. This also reflected significant suppression in the effector:target conjugate formation ratio (52% of control). The data also revealed a 150-188% increase in the number of splenic lymphocytes post-Aa injection. These effects were transient and normal levels were re-established by the fifth day. Conclusion - Aa treatment causes suppression of NK cell activity and the mode of action may be due to induction of T-suppressor cells or dilution of NK cells with other lymphoid cell populations. The degree of suppression is affected by the way in which Aa is introduced to the host. These results may contribute to the understanding of how Aa evades host defense.

AB - Objective - To examine the immune suppressive effect of Actinobacillus actinomycetemcomitans (Aa) on rat natural killer (NK) cell activity in vivo. Material and Methods - Sprague-Dawley rats were given Aa in 2 different manners: (i) by mixing Aa with food at a dose of 108 cells/rat/day for 3 months; or (ii) by a single i.m. injection of live Aa at doses of 106 and 107 cells/rat/day. NK cell activity was measured by means of a 51Cr-release assay using YAC-1 tumor cells as targets. Results - Rats that had been infected by Aa mixed with food experienced significant suppression of their NK cell activity; this reached ≈ 50% of control values at 2 and 3 months post-Aa infection. The suppression in NK cell activity was related to decreases in the extent of conjugate formation between effectors and YAC-1 target tumor cells (51.7%) and the extent of lysis of target cells (75.7%). The results also showed that addition of an admixture of Aa-treated NK cells to the control NK cells caused 75% and 53% decreases in activity at effector:target ratios of 25:1 and 50:1, respectively. In addition, a significant increase in the extent of T-suppressor cells (154.8% of control) was detected at 3 months post-Aa infection. In contrast, the single injection of live bacteria resulted in a remarkable, dose-dependent inhibition of NK cell activity (55% and 71% at doses of 106 and 107 cells/rat/day, respectively) as early as 2 days post-treatment. This also reflected significant suppression in the effector:target conjugate formation ratio (52% of control). The data also revealed a 150-188% increase in the number of splenic lymphocytes post-Aa injection. These effects were transient and normal levels were re-established by the fifth day. Conclusion - Aa treatment causes suppression of NK cell activity and the mode of action may be due to induction of T-suppressor cells or dilution of NK cells with other lymphoid cell populations. The degree of suppression is affected by the way in which Aa is introduced to the host. These results may contribute to the understanding of how Aa evades host defense.

KW - Bacterial infection

KW - Immune suppression

KW - Lymphocytes

UR - http://www.scopus.com/inward/record.url?scp=3042698781&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=3042698781&partnerID=8YFLogxK

U2 - 10.1080/00016480310015759

DO - 10.1080/00016480310015759

M3 - Article

C2 - 15267183

AN - SCOPUS:3042698781

VL - 124

SP - 621

EP - 627

JO - Acta Oto-Laryngologica

JF - Acta Oto-Laryngologica

SN - 0001-6489

IS - 5

ER -