CDs and MHCs

by Greg Crowther

A fundamental aspect of immunology is the stimulation of T cells by antigen-presenting cells (APCs). This occurs via interactions of cell-surface proteins: CD4, CD8, MHC class I, and MHC class II. (CD stands for Cluster of Differentiation, and MHC stands for Major Histocompatibility Complex.) This jingle, originally written for Biology 242 at UW-Bothell, is a mnemonic for remembering which CDs interact with which MHCs.

Cells presenting antigens will activate the T's...
But which CDs go with which MHCs?

Eight times one is eight;
Four times two is eight!

Wait; which CDs go with which MHCs?

Eight times one is eight;
Four times two is eight!

If your product is eight,
Your matching is great!

• MP3 (demo)

• sheet music

Songs like this one can be used during class meetings and/or in homework assignments. Either way, the song will be most impactful if students DO something with it, as opposed to just listening.

An initial, simple follow-up activity could be to answer the study questions below. A more extensive interaction with the song might entail (A) learning to sing it, using an audio file and/or sheet music as a guide, and/or (B) illustrating it with pictures, bodily poses, and/or bodily movements. The latter activity could begin with students identifying the most important or most challenging content of the song, and deciding how to illustrate that particular content.

(1) What does it mean to "activate the T's"?

(2) Which cells display CD proteins -- T cells or antigen-presenting cells?

(3) What are the possible CD proteins that can be displayed, and what are the possible MHC proteins?