Tumor Associated Macrophages
Macrophages are important effector cells of innate immunity. Depending on the tissue microenvironment, tumor-associated macrophages (TAM) can differentiate into either cytotoxic (M1) or tumor-promoting (M2) states. While cytotoxic M1 macrophages are typically induced by IFN-γ alone or in concert with microbial products, tumor promoting M2 macrophages are induced by IL-4 or IL-13, IL-10, IL-21, TGFβ, immune complexes, and glucocorticoids.
Application Highlight: M1 Macrophage-Mediated Tumor Cell Killing
In a recent study the secreted glycoprotein thrombospondin 1 (TSP1) was shown to be a positive modulator of innate antitumor immunity by increasing M1 macrophage recruitment and stimulating reactive oxygen species (ROS)-mediated tumor cell killing. These conclusions were drawn, in part, by using xCELLigence RTCA impedance monitoring to evaluate the effect of TSP1 on macrophage/monocyte activity when co-cultured with MDA-MB-231 breast adenocarcinoma target cells. The % cytolysis data clearly indicate that the tumoricidal activity of both differentiated U937 human monocytes (left panel) and activated ANA-1 murine macrophages (right panel) are enhanced in the presence of TSP1.
Secreted glycoprotein TSP1 increases macrophage/monocyte-mediated tumoricidal activity. MDA-MB-231 breast adenocarcinoma target cells were seeded in ACEA’s electronic microtiter plates (E-Plates) and incubated for up to 24 hours. Differentiated U937 human monocytes (left panel) or activated ANA-1 murine macrophages (right panel) were then added in the presence or absence of soluble TSP1. Figure adapted from Cancer Res. 2008;68(17):7090-9. Note that the RT-CES® described in this publication was ACEA’s first generation real-time cell analysis (RTCA) system, and has subsequently been rebranded as xCELLigence RTCA.
Key Benefits of Using xCELLigence To Study Bispecific Antibodies/BiTEs:
- Label-Free: Allowing for more physiological assay conditions; labeling or secondary assays aren’t required.
- Real-Time: Quantitative monitoring of both fast (hours) and slow (days) killing kinetics.
- Sensitive: Capable of evaluating low effector cell to target cell ratios that are physiologically relevant.
- Simple Workflow: Requires only the addition of effector cells to target cells (in the presence or absence of antibodies); homogeneous assay without additional sample handling.
- Automatic Data Plotting: RTCA software enables facile data display and objective analysis, precluding the subjective data vetting that is common to imaging-based assays.