Limits...
CD16 is indispensable for antibody-dependent cellular cytotoxicity by human monocytes

View Article: PubMed Central - PubMed

ABSTRACT

Antibody-dependent cellular cytotoxicity (ADCC) is exerted by immune cells expressing surface Fcγ receptors (FcγRs) against cells coated with antibody, such as virus-infected or transformed cells. CD16, the FcγRIIIA, is essential for ADCC by NK cells, and is also expressed by a subset of human blood monocytes. We found that human CD16− expressing monocytes have a broad spectrum of ADCC capacities and can kill cancer cell lines, primary leukemic cells and hepatitis B virus-infected cells in the presence of specific antibodies. Engagement of CD16 on monocytes by antibody bound to target cells activated β2-integrins and induced TNFα secretion. In turn, this induced TNFR expression on the target cells, making them susceptible to TNFα-mediated cell death. Treatment with TLR agonists, DAMPs or cytokines, such as IFNγ, further enhanced ADCC. Monocytes lacking CD16 did not exert ADCC but acquired this property after CD16 expression was induced by either cytokine stimulation or transient transfection. Notably, CD16+ monocytes from patients with leukemia also exerted potent ADCC. Hence, CD16+ monocytes are important effectors of ADCC, suggesting further developments of this property in the context of cellular therapies for cancer and infectious diseases.

No MeSH data available.


Related in: MedlinePlus

Pre-treatment with various stimulus enhances the ability of CD16+ monocytes to perform ADCC.(A–C) CD16+ monocytes, NK and CD16− monocytes respectively were either untreated (white bar) or pre-treated with various stimulus (grey bar). And then co-cultured with KM966-coated A549 at E:T ratio of 10:1. Data was plotted as fold difference in target cell lysis of treated to untreated effector cells. The percentage specific lysis of untreated CD16+, NK and CD16− cells were 10.1% (±4.6%), 20.6% (±10.5%) and 3.7% (±0.7%) respectively. Data are plotted as mean ± SD, n = 3. *p ≤ 0.05 and ****p ≤ 0.0001 with respect to untreated effector cells and based on One-way ANOVA (****p ≤ 0.0001 for CD16+ and NK), ns = not significant.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5037471&req=5

f6: Pre-treatment with various stimulus enhances the ability of CD16+ monocytes to perform ADCC.(A–C) CD16+ monocytes, NK and CD16− monocytes respectively were either untreated (white bar) or pre-treated with various stimulus (grey bar). And then co-cultured with KM966-coated A549 at E:T ratio of 10:1. Data was plotted as fold difference in target cell lysis of treated to untreated effector cells. The percentage specific lysis of untreated CD16+, NK and CD16− cells were 10.1% (±4.6%), 20.6% (±10.5%) and 3.7% (±0.7%) respectively. Data are plotted as mean ± SD, n = 3. *p ≤ 0.05 and ****p ≤ 0.0001 with respect to untreated effector cells and based on One-way ANOVA (****p ≤ 0.0001 for CD16+ and NK), ns = not significant.

Mentions: NK cells, CD16+ and CD16− monocytes from the same donor were pre-treated in parallel with the various stimuli before co-culture with KM966-coated A549 cells to assess ADCC. NK cells pre-treated with IL-12 and IL-15 exhibited an almost 2.5-fold increase in lysis of KM966-coated A549 over untreated NK cells. However, no enhancement in ADCC activity was observed for either CD16+ or CD16− monocytes pre-treated with IL-12 and IL-15 (Fig. 6). In contrast, CD16+ monocytes pre-treated with LPS, R848, IFNγ, S100A9 or HMGB1 showed significantly increased ADCC potency compared to untreated CD16+ monocytes (Fig. 6A). IFN-γ was the most potent inducer of ADCC activity by CD16+ monocytes. The expression of CD64, CD32a(FcγRIIa) and CD32b(FcγRIIb) on CD16+ monocytes treated with the various stimuli were not significantly altered apart from an increased in CD64 expression upon treatment with IFNγ (Supplementary Figure 3). Interestingly, all the stimuli that could enhance ADCC by CD16+ monocytes did not have any effect on ADCC exerted by NK cells or CD16− monocytes (Fig. 6B,C), nor did they enhance the capacity of CD16+ monocytes to promote antibody-independent cytotoxicity (data not shown).


CD16 is indispensable for antibody-dependent cellular cytotoxicity by human monocytes
Pre-treatment with various stimulus enhances the ability of CD16+ monocytes to perform ADCC.(A–C) CD16+ monocytes, NK and CD16− monocytes respectively were either untreated (white bar) or pre-treated with various stimulus (grey bar). And then co-cultured with KM966-coated A549 at E:T ratio of 10:1. Data was plotted as fold difference in target cell lysis of treated to untreated effector cells. The percentage specific lysis of untreated CD16+, NK and CD16− cells were 10.1% (±4.6%), 20.6% (±10.5%) and 3.7% (±0.7%) respectively. Data are plotted as mean ± SD, n = 3. *p ≤ 0.05 and ****p ≤ 0.0001 with respect to untreated effector cells and based on One-way ANOVA (****p ≤ 0.0001 for CD16+ and NK), ns = not significant.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037471&req=5

f6: Pre-treatment with various stimulus enhances the ability of CD16+ monocytes to perform ADCC.(A–C) CD16+ monocytes, NK and CD16− monocytes respectively were either untreated (white bar) or pre-treated with various stimulus (grey bar). And then co-cultured with KM966-coated A549 at E:T ratio of 10:1. Data was plotted as fold difference in target cell lysis of treated to untreated effector cells. The percentage specific lysis of untreated CD16+, NK and CD16− cells were 10.1% (±4.6%), 20.6% (±10.5%) and 3.7% (±0.7%) respectively. Data are plotted as mean ± SD, n = 3. *p ≤ 0.05 and ****p ≤ 0.0001 with respect to untreated effector cells and based on One-way ANOVA (****p ≤ 0.0001 for CD16+ and NK), ns = not significant.
Mentions: NK cells, CD16+ and CD16− monocytes from the same donor were pre-treated in parallel with the various stimuli before co-culture with KM966-coated A549 cells to assess ADCC. NK cells pre-treated with IL-12 and IL-15 exhibited an almost 2.5-fold increase in lysis of KM966-coated A549 over untreated NK cells. However, no enhancement in ADCC activity was observed for either CD16+ or CD16− monocytes pre-treated with IL-12 and IL-15 (Fig. 6). In contrast, CD16+ monocytes pre-treated with LPS, R848, IFNγ, S100A9 or HMGB1 showed significantly increased ADCC potency compared to untreated CD16+ monocytes (Fig. 6A). IFN-γ was the most potent inducer of ADCC activity by CD16+ monocytes. The expression of CD64, CD32a(FcγRIIa) and CD32b(FcγRIIb) on CD16+ monocytes treated with the various stimuli were not significantly altered apart from an increased in CD64 expression upon treatment with IFNγ (Supplementary Figure 3). Interestingly, all the stimuli that could enhance ADCC by CD16+ monocytes did not have any effect on ADCC exerted by NK cells or CD16− monocytes (Fig. 6B,C), nor did they enhance the capacity of CD16+ monocytes to promote antibody-independent cytotoxicity (data not shown).

View Article: PubMed Central - PubMed

ABSTRACT

Antibody-dependent cellular cytotoxicity (ADCC) is exerted by immune cells expressing surface Fcγ receptors (FcγRs) against cells coated with antibody, such as virus-infected or transformed cells. CD16, the FcγRIIIA, is essential for ADCC by NK cells, and is also expressed by a subset of human blood monocytes. We found that human CD16− expressing monocytes have a broad spectrum of ADCC capacities and can kill cancer cell lines, primary leukemic cells and hepatitis B virus-infected cells in the presence of specific antibodies. Engagement of CD16 on monocytes by antibody bound to target cells activated β2-integrins and induced TNFα secretion. In turn, this induced TNFR expression on the target cells, making them susceptible to TNFα-mediated cell death. Treatment with TLR agonists, DAMPs or cytokines, such as IFNγ, further enhanced ADCC. Monocytes lacking CD16 did not exert ADCC but acquired this property after CD16 expression was induced by either cytokine stimulation or transient transfection. Notably, CD16+ monocytes from patients with leukemia also exerted potent ADCC. Hence, CD16+ monocytes are important effectors of ADCC, suggesting further developments of this property in the context of cellular therapies for cancer and infectious diseases.

No MeSH data available.


Related in: MedlinePlus