I know a bunch of you are studying for boards, or are thinking about studying for boards. Any little memory aid that could help with a question or two is probably most welcome at this point. Take, for example, all those cytokines with numbers (IL-1, IL-2…). How are you supposed to remember what all of those do?! Well, today’s post, written by a brilliant immunologist, gives you a great little method for remembering the interleukins associated with Th1 and Th2 cells.

You can keep the single digit interleukins straight because they come in sequence.

1. Macrophages can produce IL-1 which activates Th cells (CD4 T cells).

2. If the macrophages also produce IL-12, this will drive the Th cells to become Th1 cells (2 to Th1, or “to” Th1).

3. If Th1 cells are induced, they will produce IL-2 (second cytokine in order) and both IL-3 and IFN-gamma (gamma is the 3rd letter of Greek alphabet and represents the 3, too).  The IFN-gamma will activate cytotoxic T cells (CD8 T cells).

4. If the macrophages produce only IL-1, this will drive the Th cells to become Th2 cells.  If Th2 cells are induced, they will produce IL-4, IL-5, and IL-6 (note that they follow in order) that drive B cells to divide and differentiate into plasma cells that produce antibody.

5. Th2 cells also produce IL-10 (“zero Th1″) which blocks macrophage production of IL-12 and thus blocks activation of Th1 cells.