And just like this one has a special cleft that can attach a certain type of protein. This one also has a special cleft as shown in the following diagram. So MHC class one are used to distinguish between healthy and infected cells. But MHC class two is actually used by the leukocytes to communicate between different types of leukocytes. And we'll see exactly what we mean by that in just a moment. So these protein complexes function in helping immune cells to communicate with one another.