Some Terms from Immunology II

As we get to the list of terms from the preceding essay, let's begin with two words no longer used, amboceptor and alexin. I begin with obsolete terms because they demonstrate how the struggle to name things, especially at the beginning of a phenomenon, often results in contrary words by investigators who often might not really like each other very much.

To understand amboceptor, which literally means "seizes both ways," we need to understand the work on blood serum done in the late 1890s at the Pasteur Institute in Paris. Jules Bordet (1870-1961) determined that blood serum contained a factor that could be analyzed into two components: a heat-resistant and heat-labile components. The heat-stable or heat-resistant component conferred immunity against specific microorganisms, while the the heat-labile component in the serum was responsible for the non-specific antimicrobial activity conferred by all normal serum. This latter component was called "complement" by Erhlich (which is the basis for the "complement" portion of the "innate immune system").

Now we are ready for amboceptor. According to his theory of the immune system, each cell has receptors on it, which he called "side-chains" (a term that has fallen out of use in favor of "receptor"). These "side chains" recognize incoming antigens. Ehrlich declared that these "side chains" had two sets of atoms on them, with one of which it unites with the immunizing body and with the other of which it unites with the "complement." These "both uniting" atoms were called amboceptor. In a 1900 lecture, he attempted to explain his theory by a set of eight diagrams. Bordet, who later referred to the diagrams as "puerile," himself wanted to throw some terminology into the mix. So, he picked up on the term alexin, coined in the early 1890s by Hans Buchner (1850-1902) to describe a class of substances found in blood-serum that had the capacity of destroying bacteria. The word alexin is derived from the Greek word alexein, which means "to ward off." So, as these early giants in the field of immunology were groping down a darkened corridor, the first battle they faced was what to call things. Ultimately it was the terms receptor and complement that prevailed.

I won't go into as much detail on any of the other terms, but I did this to show that part of our struggle for understanding relates to what to call things. If we just know the words and how they are used, we can eventually understand the field...

Starting with Zymogen

Zymogen is the last term you get to in the dictionary, so why no begin with it? The term was invented by the German scholar Heidenhain in 1875, and his method is described in this 1877 quotation: "A pancreas taken afresh from the body...contains but little ready-made ferment, though there is present in it a body which, by some kind of decomposition, gives birth to the ferment..To this body..Heidenhain has given the name of zymogen." The Greek root zymo means "leaven" or "ferment," and gen has to do with "giving birth." The concept, then, emphasizes a kind of precursor state which would possibly give birth to ferment. In current biochemistry, zymogen is also called a proenzyme, and is an "inactive enzyme precursor." Thus, a zymogen can be pictured in our mind as something that is in potential form but not yet "actualized." An enzyme can do the trick of actualization. Whereas zymogen was coined in 1875, proenzyme didn't see the light of day until 1900. I wonder why you need both terms, or if the inventer's of the latter thought that something different from zymogen was being described....

Apoptosis and Opsonization

I chose to define these two words because they have been picked up by some of our better writers in their work. Though the word apoptosis, meaning a relaxation or loosening of something, goes back to the mid-18th century, its specific use in biology only emerged in 1972 at the suggestion of Professor James Cormack, who taught Greek at the University of Aberdeen (Scotland). The word, literally meaning "falling off" (it can refer to leaves falling from trees), means "the death of individual cells, characterized by condensation and fragmentation of the nucleus and cytoplasm and usually followed by phagocytosis (eating) by other cells." Apoptosis is considered to be a regular part of the regulation of cell numbers. It is the non-traumatic "programmed cell death." This is to be distinguished from necrosis, which is death due to unexpected and accidental cell damage. Cells can be damaged in this way by toxins, radiation, heat, trauma, lack of oxygen, etc.

But guess who used the term in his writing? John Updike, in Toward the End of Time (1997): "We're not just killing these cells, Ben--we're inducing them to kill themselves, by a process called apoptosis--that's a-p-o-tosis--which the developing fetus uses to destroy embryonic gills." Nice to have the word taken out of the exclusive preserve of the scientists...

Opsonization

Though apoptosis has a long history behind it, and is even significant in ancient and modern grammar (the word ptosis has to do with the cases in inflected languages. They "fall off" from the nominative case). As the Wikipedia article defines it, "antibody opsonization is the process by which a pathogen cell is marked for ingestion and destruction by a phagocyte." Of course, a phagocyte has nothing to do with sexual orientation, but is a cell that ingests and destroys foreign matter and microorganisms through the process called phagocytosis. Thus, opsonization can be visualized as a "marking" process. Once a microorganism has the "mark of the beast" on it, then, it is marked for destruction. This reminds me of the "prick him down" command given by Marc Antony in Shakespeare's Julius Caesar, a command which would eventually catch such illustrious worthies as Cicero. But the word opsonization has an interesting meaning. Derived from the Latin obsonare/opsonare, it means "to purchase provisions" or "to cater." The first usage of the term, in 1903, included these English equivalents: "I cater for; I prepare victuals for..." Thus, opsonization "prepares victuals" for the good guys, our cells, to "eat" the bad guys.

But now to the literary usage. George Bernard Shaw already used the verb opsinize (sic) in 1906, but his literary reference to opsonin (the substance) appeared in Doctor's Dilemma (1911): "Opsonin is what you butter the disease germs with to make your white corpuscles eat them." Isn't it far better to be able to have a literary person describing these phenomena than simply a scientist?

Well, we have started our journey on some immunological terms. Let's continue it with some more words...

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