#HematologyTweetstory 14 is about blood #neutrophils: where does the term “left shift” come from? We use this term devoid of its original context, sometimes based on lab reports displayed in a column! Attached left-shifted blood & marrow pics are from @ASH_hematology Image Bank/1 
In brief, a “left-shifted” leukocyte differential is one in which the proportion of immature myeloid-series white cells, such as neutrophil bands, is increased; immature cells not normally in the blood like myelocytes or metamyelocytes may also be seen. But why is this "left"? /2
Incidentally, neutrophil bands are still sometimes called “Stab cells” because German hematologist Viktor Schilling (1883-1960) - we’ve discussed him before, not a good guy - thought the band nucleus looked like a shepherd’s crook. Rod/staff/crook = “Stab” auf Deutsch./3
We have Josef Arneth (1873-1955) to thank for the left-shift term. Arneth got his medical degree in 1897 in #Würzburg. At that time, one had to write a “habilitation thesis” with original research to join the faculty in a German university (still required today in some places)./4
Arneth’s habilitation thesis was "Die neutrophilen weissen Blutkörperchen bei Infektionskrankheiten", which he presented in 1903 & published as a book in 1904 (the year he joined Würzburg's faculty). It was a careful study of nuclear lobes of neutrophils in various conditions./5
Arneth tabulated neutrophils in 5 columns, left to right, depending on their lobe number. Soon this distribution became known as the “Arneth Count”, and it was widely used for a while, since it was easily quantifiable - an early "biomarker". /6
Papers appeared for about 30 years comparing Arneth counts in various illnesses and ethnic groups; this one is from 1908 in Australia. “Right shift” – a term I’ve never seen in the wild – indicated pernicious anemia. Sometimes the term “deflection” was used instead of "shift"./7
The Arneth count had fallen out of favor by the Second World War, but “left-shift” term hung around, because by then it was being reinforced by mechanical counters. A technician reviewing a blood smear might use a counter like this 1920s model to tabulate white cell types.../8
Victor Hoffbrand of the Royal Free has teased me for using the term blood "smear”. “It’s a blood *film*, David. ‘Smear’ sounds so distasteful.” Fair enough, Victor. We got along well enough to write a book, which came out last month @wiley and will set you back a mere $64.99./9
One can still find mechanical counters in many #hematology laboratories. When I was a hematology fellow and had to count manual diffs, there was one of these next to the microscope. Buttons for immature cells – myelocytes, bands etc – were to the left of those for mature cells.
Mechanical counters are seen in a few other settings. For instance, when I played Little League baseball as a lad, umpires used ball/strike counters. It was disheartening to hear the umpire shout “strike” as the ball whizzed past, then hear a little click of doom on the counter.
Even today the convention is to depict WBC differentiation from left to right, as in this 2018 diagram from Lawrence SM et al MMBR @ASMicrobiology review on neutrophil ontogeny. /12
While most languages are written left to right (and/or top to bottom, like Japanese tategaki), I wonder if an “Arneth count” had instead been described by an Arabic or Persian physician. Would we speak of *right* shift, or routinely depict blood cell differentiation R to L?🤷♂️/End
