Immune system cells differentiate healthy versus unhealthy cells in the body by examining what part of the cell?

Answer is glycocalyx.

Explanation:

Glycocalyx is like a coat that covering the outside of organism such as bacteria. It composed or made up of glycoproteins, glycolipids and polysaccharides.

The function the glycocalyx found on the bacteria, is that, it is like a protective coat for the bacterial cell from the host reactor, which is the immune system/

There are two major types of glycocaltx and they are capsules and slime layers.