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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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Early immune complex-mediated responses condition later events. PBMCs were cultured for a total of 18 h with TIV and FCS or immune AB plasma (AB) in the presence or absence of the MMP inhibitor TAP1-1 (A–C) or the D1(A12) blocking antibody to ADAM17 (D–F) and the relevant negative controls (DMSO and mIgG1, respectively). CD16 (MFI) (A,D), CD107a (%) (B,E), and CD25 (C,F) expression were assessed by flow cytometry. TAPI-1, DMSO, D1(A12), or mIgG1 were added either 30 min prior to (−0.5), or 6 h after (+6) TIV antigen. Data are presented for eight different individuals. Paired comparisons between conditions were made using the Mann–Whitney U test. *p < 0.05, **p < 0.01, ***p < 0.001.
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Figure 5: Early immune complex-mediated responses condition later events. PBMCs were cultured for a total of 18 h with TIV and FCS or immune AB plasma (AB) in the presence or absence of the MMP inhibitor TAP1-1 (A–C) or the D1(A12) blocking antibody to ADAM17 (D–F) and the relevant negative controls (DMSO and mIgG1, respectively). CD16 (MFI) (A,D), CD107a (%) (B,E), and CD25 (C,F) expression were assessed by flow cytometry. TAPI-1, DMSO, D1(A12), or mIgG1 were added either 30 min prior to (−0.5), or 6 h after (+6) TIV antigen. Data are presented for eight different individuals. Paired comparisons between conditions were made using the Mann–Whitney U test. *p < 0.05, **p < 0.01, ***p < 0.001.

Mentions: Our previous studies have suggested that early, antibody-dependent mechanisms may synergize with antigen-specific T cell responses to enhance NK cell responses to vaccines (3, 23). Since sustained expression of CD16 in the presence of ADAM17/MMP inhibitors led to enhanced degranulation (Figure 5), we investigated whether prevention of CD16 shedding would affect other NK cell responses. ADAM17/MMP blockade had no impact on IgG–TIV-induced CD69 expression, nor was there any impact on CD25 expression after 6 h of culture (Figure S2 in Supplementary Material). However in 18 h cultures, addition of TAPI-1 (Figures 5A–C) or blocking antibody to ADAM17 (Figures 5D–F) 30 min before the start of the culture (time – 0.5 h) not only sustained CD16 expression (Figures 5A,D) and enhanced CD107a expression (Figure 5B) but also significantly enhanced CD25 expression compared to control cultures (Figures 5C,F). However, when addition of TAPI-1 or anti-ADAM17 was delayed for 6 h after the initiation of cultures (+ 6 h) CD16 expression could not be rescued (Figures 5A,D) and there was no enhancement of degranulation or CD25 expression (Figures 5B,C,E,F).


Sustained Immune Complex-Mediated Reduction in CD16 Expression after Vaccination Regulates NK Cell Function
Early immune complex-mediated responses condition later events. PBMCs were cultured for a total of 18 h with TIV and FCS or immune AB plasma (AB) in the presence or absence of the MMP inhibitor TAP1-1 (A–C) or the D1(A12) blocking antibody to ADAM17 (D–F) and the relevant negative controls (DMSO and mIgG1, respectively). CD16 (MFI) (A,D), CD107a (%) (B,E), and CD25 (C,F) expression were assessed by flow cytometry. TAPI-1, DMSO, D1(A12), or mIgG1 were added either 30 min prior to (−0.5), or 6 h after (+6) TIV antigen. Data are presented for eight different individuals. Paired comparisons between conditions were made using the Mann–Whitney U test. *p < 0.05, **p < 0.01, ***p < 0.001.
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Figure 5: Early immune complex-mediated responses condition later events. PBMCs were cultured for a total of 18 h with TIV and FCS or immune AB plasma (AB) in the presence or absence of the MMP inhibitor TAP1-1 (A–C) or the D1(A12) blocking antibody to ADAM17 (D–F) and the relevant negative controls (DMSO and mIgG1, respectively). CD16 (MFI) (A,D), CD107a (%) (B,E), and CD25 (C,F) expression were assessed by flow cytometry. TAPI-1, DMSO, D1(A12), or mIgG1 were added either 30 min prior to (−0.5), or 6 h after (+6) TIV antigen. Data are presented for eight different individuals. Paired comparisons between conditions were made using the Mann–Whitney U test. *p < 0.05, **p < 0.01, ***p < 0.001.
Mentions: Our previous studies have suggested that early, antibody-dependent mechanisms may synergize with antigen-specific T cell responses to enhance NK cell responses to vaccines (3, 23). Since sustained expression of CD16 in the presence of ADAM17/MMP inhibitors led to enhanced degranulation (Figure 5), we investigated whether prevention of CD16 shedding would affect other NK cell responses. ADAM17/MMP blockade had no impact on IgG–TIV-induced CD69 expression, nor was there any impact on CD25 expression after 6 h of culture (Figure S2 in Supplementary Material). However in 18 h cultures, addition of TAPI-1 (Figures 5A–C) or blocking antibody to ADAM17 (Figures 5D–F) 30 min before the start of the culture (time – 0.5 h) not only sustained CD16 expression (Figures 5A,D) and enhanced CD107a expression (Figure 5B) but also significantly enhanced CD25 expression compared to control cultures (Figures 5C,F). However, when addition of TAPI-1 or anti-ADAM17 was delayed for 6 h after the initiation of cultures (+ 6 h) CD16 expression could not be rescued (Figures 5A,D) and there was no enhancement of degranulation or CD25 expression (Figures 5B,C,E,F).

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