Dear Juliane,

we use PM routinely in our lab and in our hands they always react like an M1 macrophage. We never observed M2- or M0-like behaviour. After infection or stimulation with PAMPs they produce tons of pro-inflammtory cytokines and chemokines in 5 hours (while BMDM and thioglycolate-elicitied PM take much longer, nearly 24h). They produce very quick a robust amount of extracellular and cytosolic ROS and show quick and effective phagocytosis of many bacteria.

I, in general, consider naive PM (not elicited PM) as M1 phenotype. For several examples of PM responses after bacterial infection, please have a look at our papers:

Article The β2 Integrin Mac-1 Induces Protective LC3-Associated Phag...

Article Mitochondrial reactive oxygen species enable proinflammatory...

For a detailed description, please have also a look at our methods paper:

Article Highly Efficient Transfection of Primary Macrophages with In...

For any further information or protocols, feel free to ask any time.

All the best and stay healthy,

Marc

Hello Marc,

thanks a lot for your detailed answer. I will check your papers and figure it out.

Have a great day!

Jule

You are very welcome. If you have any further questions, please ask.

You too :)

I have tried 50 ng/mL IFN-γ and/or 10-20 ng/mL of LPS for M1 activation and 20 ng/mL IL-4 and/or IL13 for M2 activation.

Within M2, IL-4 and/or IL13 stimulation was shown to lead towards M2a activation. Similarly, stimulation with immune complexes lead towards M2b, IL10 and/or and glucocorticoids towards M2c and IL6 towards M2d activation !!

Thanks Vinod!

In addition, I want to point to our recent paper, in which we investigated a new variant of non-canonical autophagy in macrophages infected with Listeria monocytogenes. Importantly, this paper also shows that not every macrophage type is suitable for every study and experimental analysis. We show that BMDM have much less of the ROS-generating enzyme Nox2 and therefore produce nearly no extracellular/phagosomal ROS. Only after pro-inflammatory priming, Nox2 protein levels and ROS production nearly reach levels of ex vivo peritoneal macrophages.

If you like, please have a look at:

Article Macrophages target Listeria monocytogenes by two discrete no...

All the best and stay healthy,

Marc