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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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Downregulation of CD16 correlates with degranulation. (A,B) Flow cytometry gating strategy for CD107a expression on CD56+ NK cells cultured with immune plasma (A) with or (B) without TIV. (C,D) Proportions of CD56dim, CD56dimCD57− and CD56dim CD57+ NK cells expressing CD107a after culture of baseline PBMC for 6 h with TIV (shaded bars) or without TIV (open bars) in the presence of baseline (0) or 2 weeks post-vaccination (2) plasma. Individuals (n = 10 per group) were vaccinated I.M. with TIV (C) or I.N. with LAIV (D). (E,F) Correlation between CD16 expression (MFI) and frequency of CD107a-expressing NK cells within CD57−(E) and CD57+(F) NK cells after culture for 6 h with TIV and immune plasma. Comparisons between conditions were made using Mann–Whitney U test. Correlations were performed using linear regression. *p < 0.05, **p < 0.01, ***p < 0.001.
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Figure 3: Downregulation of CD16 correlates with degranulation. (A,B) Flow cytometry gating strategy for CD107a expression on CD56+ NK cells cultured with immune plasma (A) with or (B) without TIV. (C,D) Proportions of CD56dim, CD56dimCD57− and CD56dim CD57+ NK cells expressing CD107a after culture of baseline PBMC for 6 h with TIV (shaded bars) or without TIV (open bars) in the presence of baseline (0) or 2 weeks post-vaccination (2) plasma. Individuals (n = 10 per group) were vaccinated I.M. with TIV (C) or I.N. with LAIV (D). (E,F) Correlation between CD16 expression (MFI) and frequency of CD107a-expressing NK cells within CD57−(E) and CD57+(F) NK cells after culture for 6 h with TIV and immune plasma. Comparisons between conditions were made using Mann–Whitney U test. Correlations were performed using linear regression. *p < 0.05, **p < 0.01, ***p < 0.001.

Mentions: As CD16 downregulation is IgG–Ag-mediated and, thus, likely linked to ADCC, we explored the relationship between influenza vaccination, NK cell CD16 expression and degranulation (Figure 3). PBMCs were collected at baseline from TIV- and LAIV-vaccinated donors and cultured for 6 h with or without TIV and autologous plasma collected at baseline or 2 weeks after vaccination. Sample plots for analysis of CD107a expression are shown for NK cells cultured in autologous plasma with TIV or, as a negative control, without TIV (Figures 3A,B). Modest, but statistically significant, degranulation was seen in cells cultured with baseline (week 0) plasma for both TIV-vaccinated (Figure 3C) and LAIV-vaccinated (Figure 3D) individuals, again likely reflecting the presence of anti-influenza antibodies due to environmental exposure. Degranulation was, however, further enhanced in the presence of post-vaccination plasma (2 weeks) from TIV-vaccinated individuals (Figure 3C) but not from individuals receiving LAIV (Figure 3D). As expected, degranulation responses were stronger among CD57+ NK cells than among CD57− NK cells and CD16 expression was strongly inversely associated with CD107a expression (Figures 3E,F). As expected, for TIV-vaccinated donors, the extent of CD107a expression was dependent upon plasma concentration, and was greater among CD57+ NK cells than among CD57− NK cells, although there was no evidence that NKG2C+ cells responded more strongly than NKG2C− cells (Supplementary Figure S1 C,D).


Sustained Immune Complex-Mediated Reduction in CD16 Expression after Vaccination Regulates NK Cell Function
Downregulation of CD16 correlates with degranulation. (A,B) Flow cytometry gating strategy for CD107a expression on CD56+ NK cells cultured with immune plasma (A) with or (B) without TIV. (C,D) Proportions of CD56dim, CD56dimCD57− and CD56dim CD57+ NK cells expressing CD107a after culture of baseline PBMC for 6 h with TIV (shaded bars) or without TIV (open bars) in the presence of baseline (0) or 2 weeks post-vaccination (2) plasma. Individuals (n = 10 per group) were vaccinated I.M. with TIV (C) or I.N. with LAIV (D). (E,F) Correlation between CD16 expression (MFI) and frequency of CD107a-expressing NK cells within CD57−(E) and CD57+(F) NK cells after culture for 6 h with TIV and immune plasma. Comparisons between conditions were made using Mann–Whitney U test. Correlations were performed using linear regression. *p < 0.05, **p < 0.01, ***p < 0.001.
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Figure 3: Downregulation of CD16 correlates with degranulation. (A,B) Flow cytometry gating strategy for CD107a expression on CD56+ NK cells cultured with immune plasma (A) with or (B) without TIV. (C,D) Proportions of CD56dim, CD56dimCD57− and CD56dim CD57+ NK cells expressing CD107a after culture of baseline PBMC for 6 h with TIV (shaded bars) or without TIV (open bars) in the presence of baseline (0) or 2 weeks post-vaccination (2) plasma. Individuals (n = 10 per group) were vaccinated I.M. with TIV (C) or I.N. with LAIV (D). (E,F) Correlation between CD16 expression (MFI) and frequency of CD107a-expressing NK cells within CD57−(E) and CD57+(F) NK cells after culture for 6 h with TIV and immune plasma. Comparisons between conditions were made using Mann–Whitney U test. Correlations were performed using linear regression. *p < 0.05, **p < 0.01, ***p < 0.001.
Mentions: As CD16 downregulation is IgG–Ag-mediated and, thus, likely linked to ADCC, we explored the relationship between influenza vaccination, NK cell CD16 expression and degranulation (Figure 3). PBMCs were collected at baseline from TIV- and LAIV-vaccinated donors and cultured for 6 h with or without TIV and autologous plasma collected at baseline or 2 weeks after vaccination. Sample plots for analysis of CD107a expression are shown for NK cells cultured in autologous plasma with TIV or, as a negative control, without TIV (Figures 3A,B). Modest, but statistically significant, degranulation was seen in cells cultured with baseline (week 0) plasma for both TIV-vaccinated (Figure 3C) and LAIV-vaccinated (Figure 3D) individuals, again likely reflecting the presence of anti-influenza antibodies due to environmental exposure. Degranulation was, however, further enhanced in the presence of post-vaccination plasma (2 weeks) from TIV-vaccinated individuals (Figure 3C) but not from individuals receiving LAIV (Figure 3D). As expected, degranulation responses were stronger among CD57+ NK cells than among CD57− NK cells and CD16 expression was strongly inversely associated with CD107a expression (Figures 3E,F). As expected, for TIV-vaccinated donors, the extent of CD107a expression was dependent upon plasma concentration, and was greater among CD57+ NK cells than among CD57− NK cells, although there was no evidence that NKG2C+ cells responded more strongly than NKG2C− cells (Supplementary Figure S1 C,D).

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