The IL-10GFP (VeRT-X) mouse strain is not suitable for the detection of IL-10 production by granulocytes during lung inflammation

The clear and unequivocal identification of immune effector functions is essential to understand immune responses. The cytokine IL-10 is a critical immune regulator and was shown, for example, to limit pathology during various lung diseases. However, the clear identification of IL-10-producing cells is challenging and, therefore, reporter mouse lines were developed to facilitate their detection. Several such reporter lines utilize GFP, including the IL-10(GFP) (VeRT-X) reporter strain studied here. In line with previous reports, we found that this IL-10(GFP) line faithfully reports on the IL-10 production of lymphoid cells. However, we show that the IL-10(GFP) reporter is not suitable to analyse IL-10 production of myeloid cells during inflammation. During inflammation, the autofluorescence of myeloid cells increased to an extent that entirely masked the IL-10-specific GFP-signal. Our data illustrate a general and important technical caveat using GFP-reporter lines for the analysis of myeloid cells and suggest that previous reports on effector functions of myeloid cells using such GFP-based reporters might require re-evaluation.

Automated summary

The identification of immune effector functions, particularly those involving IL-10 production, is crucial for understanding immune responses. While IL-10(GFP) reporter lines can accurately report on IL-10 production by lymphoid cells, they may not be suitable for analyzing myeloid cell IL-10 production, as autofluorescence can interfere with GFP signals. This highlights a potential technical limitation when using GFP-reporter lines for studying myeloid cells in inflammation.