cell markers

So how do you recognize another DUT student, even if you dont know him/her? Well these days, its easy cos they are probably looking bored, waiting for lectures to start.
Okay so how do you recognize academic staff of the Biomed dept? I suppose because we look like we belong here, and may have a look of authority about us? I'm not actually sure.
The point i am trying to make is that we use non verbal clues to identify other people.
So how do you suppose cells in the body recognise each other? Do you think they carry signs that say: Hello. I am a Tc cell. Who are you? I think noT!!!!!!!!!!!!!

All cells express (important word used here, remember it) cell markers. A cell marker is a structure found on the surface of a cell. It is not part of the cell membrane, so it cannot be drawn as part of the cell membrane. It is like an address for cells. Different cell markers are found on different cells. Cells 'talk' to each other via cell markers.
Now these cell markers do not actually connect with each other, rather they interact with each other, meaning there is a distinct clear space between each cell marker.
now to the drawing: a spherical shape represents cells. Any shape will represent a cell marker, BUT remember the lock and key mechanism thingy!!!
so i want you to draw me 2 cells interacting with each other via cell markers which 'fit' into each other. NB! no contact between the cell markers. Cell markers are structures on the surface of the cells
now label them as follows:
Tc cell expressing CD8
Th cell expressing CD4

so if we had to write down in words what you just drew:
a Tc cell expressing CD8 interacts with CD4 expressed by Th cell.

makes sense??? if it doesnt, let me know please . Enough for today. Rest now