My first leap into the learning pool was discouraging. Gail and I had just spent a few days in Tennessee visiting my son's family. The flight from Knoxville back home was about two hours and I planned on spending the time reading the first few chapters of Abbas et al's book. Chapter one, an overview, wasn't too bad. But subsequent chapters left my neurons jumbled. There were two major problems: complexity and jargon.
I once tried to explain baseball to someone from India. It was near impossible. The number of interacting parts of the game piled upon one another into an unholy mess. The immune system is at least 100 fold more complicated. An added difficulty is the fact that each of the players has two or more names. For example, one of the major cells in immunity is called the "killer T cell". OK. That's a piece of jargon that I can live with. It's both descriptive and memorable. But the same cell more frequently goes by the title "cytotoxic lymphocyte". That's quite a mouthful too, so, apparently in the interest of brevity, immunologists shorten it to "CTL". The problem is that in all my sources "CTL" is defined on one page and then used again a few pages later. Reading a page full of these initialisms requires repeated trips to the index or access to a scorecard.
Just as I did for Sompayrac's book, I made a list of the initialisms that I encountered in chapter four of Abbas et al. There were 20. Some like "NK" (natural killer) and "DC" (dendritic cells) seemed like logical constructions and were easily remembered. Others like "ITIMs" (immunoreceptor tyrosine-based activation motifs) were clearly created to torture readers. In my future writing, I promise to keep abbreviations to a minimum even if I don't eliminate them entirely.
But there are further difficulties. Almost all the major players in the immune response are proteins. That's because proteins are the primary machines in cells, carrying out almost all cellular functions. Unfortunately for persons trying to learn immunology, there are many hundreds of different proteins involved in the immune response. Not only that, but they interact with each other in extraordinarily complex ways. Worse yet, many have names that are historical in origin, sometimes having nothing to do with what they do in the immune response. Take for example, a class of proteins called "Toll-like receptors". Toll was a protein first identified in fruit flies way back in 1985. The Toll gene and its protein product help fly embryos establish their dorsal/ventral axis (in simpler terms they set up the top and bottom of the embryo). It wasn't until 15 years later that they were found to play an entirely different role in the innate immune reaction, something which I'll discuss later. Because of the numbers of proteins and their obscure origin, trying to memorize their names, let alone learning how they interact with each other to perform their functions, are Sisyphean tasks for the beginner. And of course, for me too.
Despite these challenges, I pressed on. All the references that I encountered begin the study of immunology in the same way. They distinguish between two basic kinds of immunity: innate and adaptive. I'll begin the next blog entry with a description of the innate system.