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Sustained Immune Complex-Mediated Reduction in CD16 Expression after Vaccination Regulates NK Cell Function

View Article: PubMed Central - PubMed

ABSTRACT

Cross-linking of FcγRIII (CD16) by immune complexes induces antibody-dependent cellular cytotoxicity (ADCC) by natural killer (NK) cells, contributing to control of intracellular pathogens; this pathway can also be targeted for immunotherapy of cancerous or otherwise diseased cells. However, downregulation of CD16 expression on activated NK cells may limit or regulate this response. Here, we report sustained downregulation of CD16 expression on NK cells in vivo after intramuscular (but not intranasal) influenza vaccination. CD16 downregulation persisted for at least 12 weeks after vaccination and was associated with robust enhancement of influenza-specific plasma antibodies after intramuscular (but not intranasal) vaccination. This effect could be emulated in vitro by co-culture of NK cells with influenza antigen and immune serum and, consistent with the sustained effects after vaccination, only very limited recovery of CD16 expression was observed during long-term in vitro culture of immune complex-treated cells. CD16 downregulation was most marked among normally CD16high CD57+ NK cells, irrespective of NKG2C expression, and was strongly positively associated with degranulation (surface CD107a expression). CD16 downregulation was partially reversed by inhibition of ADAM17 matrix metalloprotease, leading to a sustained increase in both CD107a and CD25 (IL-2Rα) expression. Both the degranulation and CD25 responses of CD57+ NK cells were uniquely dependent on trivalent influenza vaccine-specific IgG. These data support a role for CD16 in early activation of NK cells after vaccination and for CD16 downregulation as a means to modulate NK cell responses and maintain immune homeostasis of both antibody and T cell-dependent pathways.

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Bi-directional cross-talk between CD16-mediated and cytokine-mediated pathways of NK cell activation. (A–C) PBMCs were cultured for 18 h with or without TIV in the presence of immune plasma (IgG+) or IgG-depleted immune plasma (IgG−) or after treatment with anti-IL-2 neutralizing antibody or isotype-matched control and expression of CD16 MFI (A), CD107a (%) (B), or CD25 (%) (C) on CD56dim, CD56dimCD57−, and CD56dimCD57+ NK cells was assessed by flow cytometry. (D–F) PBMCs were cultured for 18 h with or without IL-12 (5 ng/ml) combined with IL-18 (50 ng/ml) and expression of CD16 MFI (D), CD107a (%) (E), or CD25 (%) (F) on CD56dim, CD56dimCD57−, and CD56dimCD57+ NK cells was assessed by flow cytometry. Paired comparisons were made using the Mann–Whitney U test. *p < 0.05, **p < 0.01, ***p < 0.001.
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Figure 6: Bi-directional cross-talk between CD16-mediated and cytokine-mediated pathways of NK cell activation. (A–C) PBMCs were cultured for 18 h with or without TIV in the presence of immune plasma (IgG+) or IgG-depleted immune plasma (IgG−) or after treatment with anti-IL-2 neutralizing antibody or isotype-matched control and expression of CD16 MFI (A), CD107a (%) (B), or CD25 (%) (C) on CD56dim, CD56dimCD57−, and CD56dimCD57+ NK cells was assessed by flow cytometry. (D–F) PBMCs were cultured for 18 h with or without IL-12 (5 ng/ml) combined with IL-18 (50 ng/ml) and expression of CD16 MFI (D), CD107a (%) (E), or CD25 (%) (F) on CD56dim, CD56dimCD57−, and CD56dimCD57+ NK cells was assessed by flow cytometry. Paired comparisons were made using the Mann–Whitney U test. *p < 0.05, **p < 0.01, ***p < 0.001.

Mentions: The data presented in Figure 5 are consistent with a role for antigen–antibody complex signaling via CD16 in induction of CD25 as well as in degranulation/cytotoxicity. To explore this further, PBMCs were cultured with TIV for 18 h in the presence of intact immune plasma or immune plasma that had been depleted of IgG by passage over a protein G column (Figure 6). The concentration of anti-TIV–IgG in intact plasma was 413.4 arbitrary ELISA units (AEU)/ml and this was reduced to 7.4 AEU/ml after protein G depletion.


Sustained Immune Complex-Mediated Reduction in CD16 Expression after Vaccination Regulates NK Cell Function
Bi-directional cross-talk between CD16-mediated and cytokine-mediated pathways of NK cell activation. (A–C) PBMCs were cultured for 18 h with or without TIV in the presence of immune plasma (IgG+) or IgG-depleted immune plasma (IgG−) or after treatment with anti-IL-2 neutralizing antibody or isotype-matched control and expression of CD16 MFI (A), CD107a (%) (B), or CD25 (%) (C) on CD56dim, CD56dimCD57−, and CD56dimCD57+ NK cells was assessed by flow cytometry. (D–F) PBMCs were cultured for 18 h with or without IL-12 (5 ng/ml) combined with IL-18 (50 ng/ml) and expression of CD16 MFI (D), CD107a (%) (E), or CD25 (%) (F) on CD56dim, CD56dimCD57−, and CD56dimCD57+ NK cells was assessed by flow cytometry. Paired comparisons were made using the Mann–Whitney U test. *p < 0.05, **p < 0.01, ***p < 0.001.
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Related In: Results  -  Collection

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Figure 6: Bi-directional cross-talk between CD16-mediated and cytokine-mediated pathways of NK cell activation. (A–C) PBMCs were cultured for 18 h with or without TIV in the presence of immune plasma (IgG+) or IgG-depleted immune plasma (IgG−) or after treatment with anti-IL-2 neutralizing antibody or isotype-matched control and expression of CD16 MFI (A), CD107a (%) (B), or CD25 (%) (C) on CD56dim, CD56dimCD57−, and CD56dimCD57+ NK cells was assessed by flow cytometry. (D–F) PBMCs were cultured for 18 h with or without IL-12 (5 ng/ml) combined with IL-18 (50 ng/ml) and expression of CD16 MFI (D), CD107a (%) (E), or CD25 (%) (F) on CD56dim, CD56dimCD57−, and CD56dimCD57+ NK cells was assessed by flow cytometry. Paired comparisons were made using the Mann–Whitney U test. *p < 0.05, **p < 0.01, ***p < 0.001.
Mentions: The data presented in Figure 5 are consistent with a role for antigen–antibody complex signaling via CD16 in induction of CD25 as well as in degranulation/cytotoxicity. To explore this further, PBMCs were cultured with TIV for 18 h in the presence of intact immune plasma or immune plasma that had been depleted of IgG by passage over a protein G column (Figure 6). The concentration of anti-TIV–IgG in intact plasma was 413.4 arbitrary ELISA units (AEU)/ml and this was reduced to 7.4 AEU/ml after protein G depletion.

View Article: PubMed Central - PubMed

ABSTRACT

Cross-linking of Fc&gamma;RIII (CD16) by immune complexes induces antibody-dependent cellular cytotoxicity (ADCC) by natural killer (NK) cells, contributing to control of intracellular pathogens; this pathway can also be targeted for immunotherapy of cancerous or otherwise diseased cells. However, downregulation of CD16 expression on activated NK cells may limit or regulate this response. Here, we report sustained downregulation of CD16 expression on NK cells in vivo after intramuscular (but not intranasal) influenza vaccination. CD16 downregulation persisted for at least 12&thinsp;weeks after vaccination and was associated with robust enhancement of influenza-specific plasma antibodies after intramuscular (but not intranasal) vaccination. This effect could be emulated in vitro by co-culture of NK cells with influenza antigen and immune serum and, consistent with the sustained effects after vaccination, only very limited recovery of CD16 expression was observed during long-term in vitro culture of immune complex-treated cells. CD16 downregulation was most marked among normally CD16high CD57+ NK cells, irrespective of NKG2C expression, and was strongly positively associated with degranulation (surface CD107a expression). CD16 downregulation was partially reversed by inhibition of ADAM17 matrix metalloprotease, leading to a sustained increase in both CD107a and CD25 (IL-2R&alpha;) expression. Both the degranulation and CD25 responses of CD57+ NK cells were uniquely dependent on trivalent influenza vaccine-specific IgG. These data support a role for CD16 in early activation of NK cells after vaccination and for CD16 downregulation as a means to modulate NK cell responses and maintain immune homeostasis of both antibody and T cell-dependent pathways.

No MeSH data available.


Related in: MedlinePlus