Hello Joydeep Roy

There is no such fixed ratio regarding the cell density of cancer cells versus the macrophages for co-culture. The ratio of macrophages : tumor cells need to be adjusted depending on the aggressiveness of the tumor cells and the origin (cell lines or primary cells) of the macrophages. This adjustment is necessary because the interactions between macrophages and tumor cells, including phagocytosis, can be affected by the specific characteristics of both cell types.

If the tumor is more aggressive, it may require higher ratios of macrophages to potentially suppress tumor growth and enhance the immune response. The macrophage origin also plays an important role. Cell line macrophages may behave differently than primary (in vivo) macrophages, affecting their interactions with tumor cells. The process of phagocytosis wherein macrophages engulf and kill tumor cells, can be influenced by the cell density, particularly in co-cultures.

In co-cultures of macrophages and cancer cells, the optimal ratio is a subject of ongoing research, but I have come across some studies which suggest a 30% macrophage to 70% cancer cell ratio. This may be a good starting point to mimic in vivo conditions. You should try this out.

Good Luck!

My suggestion is to start with experimenting with different percentages with known (standardized) number of cell concentrations both for macrophages and cancer cells. Results from at least 5 - 7 different percentages would provide you a better starting point for your research.

It depends. For example, we use a 1:10 ratio for direct co-culture of differentiated THP-1 and A549 cell lines, based on previous research. I suggest the same approach as my colleagues: start with different ratios and observe how the cells behave. Alternatively, if you have any information about the ratio of these cells in vivo, try to mimic those conditions.