I've always been told not to use after 20 passages. I've noticed that around the 15th passage cells start to slow down. All my experiments were performed around the 3rd and 5th passage.

What he said^^^^^ :)

I agree. I have noticed that around the 20th passage, their phenotype can change.

Thank you all

It depends on what you check, i am checking endotoxin neutralization and after the 10th passage they are highly activated.

I used up to 40th passage. They are fine for NO assay after LPS stimulation