The Sugars

May 23, 2026 • 1900 to 1930, the Institute of Pathological Anatomy in Vienna, Mount Sinai Hospital in New York, and the Karolinska Institutet in Stockholm • 5 min read

Verified 12 claims · 6 searches · 1 pass

Split-frame editorial illustration. Left half: the small first-floor laboratory of the Institute of Pathological Anatomy on Spitalgasse in central Vienna on a cool winter afternoon in 1900. Karl Landsteiner stands in three-quarter rear silhouette at the polished oak laboratory bench in cream linen laboratory apron over charcoal-grey wool three-piece suit, slim small wire-rimmed reading spectacles, short dark hair parted neatly, short dark moustache, slate-blue silk bow tie at the throat. He holds a small hand-blown glass pipette over a hand-blown glass test-tube rack at the centre of the bench. The rack holds about twenty test tubes, each containing a cream serum layer above a small pellet of red blood cells; three of the tubes are clearly clumped, showing small dark oxblood-red grains suspended in the serum (the agglutination), while the others remain clear. A small porcelain centrifuge bowl sits on the lower-left of the bench. A hand-bound leather laboratory notebook lies open at the lower-right with soft umber pen-strokes in brown iron-gall ink. A brass-and-glass green-shaded laboratory lamp at the far right throws strong warm amber light across the tubes. Glass-stoppered period chemical jars line the painted-wood shelf on the back wall. A small framed lithograph of an anatomical heart hangs on the side wall. A tall narrow sash window at the back wall opens onto a cool slate-blue Vienna winter courtyard with distant Habsburg-era rooftops. Right half: a stylised abstract super-resolution microscope view of the glycocalyx on a single human cell at the Max Planck Institute for the Science of Light in Erlangen in May 2026. Below the centre of the right half, a soft pinkish-amber curved horizontal band represents the cell's outer lipid bilayer membrane. Rising above it, a forest of branched sugar polymers rendered as connected coloured beads: cool electric-cyan sialic acid, soft magenta galactose, soft amber N-acetylglucosamine, and soft cream fucose units, attached at the bottom to small soft slate-blue painted membrane-protein anchors emerging from the membrane. The glycocalyx forest is perhaps three to five hundred nanometres tall in the visualisation. Small fluorescent cool electric-cyan and soft magenta DNA-tagged lectin probes are scattered in the upper dark-field. A faint cool electric-cyan super-resolution scan grid runs across the upper portion of the visualisation. The cool deep electric-cyan and slate-blue microscope dark-field background fades into very dark blue at the very top. A continuous warm amber-and-cool electric-cyan horizon ribbon runs edge to edge across the centre of the frame, joining the 1900 Vienna test-tube grid on the left to the 2026 super-resolution glycocalyx on the right.

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The Echo

Karl Landsteiner's 1900 discovery of the ABO blood groups by mixing the sera of his colleagues at the University of Vienna's Institute of Pathological Anatomy with their red blood cells in glass test tubes and observing agglutination, his 1900 footnote in Zentralblatt für Bakteriologie, his full 1901 paper in the Wiener klinische Wochenschrift, the 1902 identification of the fourth (AB) group by Alfred von Decastello and Adriano Sturli in the same Vienna laboratory, the seven-year clinical gap until Reuben Ottenberg performed the first deliberately matched transfusion at Mount Sinai Hospital in New York in 1907, the routine adoption of typed transfusion during the First World War that saved tens of millions of lives, and the 1930 Nobel Prize in Physiology or Medicine. (1900 to 1930, the Institute of Pathological Anatomy in Vienna, Mount Sinai Hospital in New York, and the Karolinska Institutet in Stockholm) ↔ A May 2026 Nature Nanotechnology paper by Möckl and colleagues at the Max Planck Institute for the Science of Light in Erlangen introduces Glycan Atlasing, a technique that combines DNA-tagged lectins, metabolic oligosaccharide engineering and super-resolution microscopy to map every glycan on the surface of a cell at nanometre resolution; the technique distinguishes cancerous from healthy tissue and tracks immune-cell activation by the spatial pattern of sugars alone. (Today)

In the winter of 1900, in a small first-floor laboratory at the Institute of Pathological Anatomy on Spitalgasse in central Vienna, a thirty-two-year-old Austrian physician named Karl Landsteiner pricked the fingers of five of his colleagues, separated the painterly red cells from the serum in each sample with a small porcelain centrifuge, and began to mix every serum with every set of cells in a grid of small glass test tubes. He was looking for the reason that blood transfusions had been killing roughly half of the people who received them.

Some tubes did nothing. The serum and the red cells sat together quietly. The tubes that did something turned cloudy. The red cells in those tubes had clumped into small dark grains visible against the cream-coloured serum, as if the cells had been recognised as foreign and condemned by the chemistry of the donor. Landsteiner recognised at once that he had a sorting principle.

He wrote up the result the following autumn as a footnote in a longer paper on the agglutinating action of normal blood serum, published in the German journal Zentralblatt für Bakteriologie in 1900. The full account followed in 1901 in the Wiener klinische Wochenschrift under the title Ueber Agglutinationserscheinungen normalen menschlichen Blutes, on the agglutinating phenomena of normal human blood. He had identified three groups, which he called A, B and C. The C group was relabelled O within a few years, because the clumping pattern made it the absence of either of the other two antigens. A fourth group, AB, the rarest, was identified the following year by two of his colleagues, Alfred von Decastello and Adriano Sturli, working in the same Vienna laboratory.

The reason for the clumping was a sugar. Not the sugar you can taste. A sugar molecule attached to the outside of the red blood cell, sitting at the very tip of a slim chain of other sugars that protruded into the bloodstream. Group A had one sugar at the tip. Group B had another. Group O had neither. Group AB had both. The painterly chemistry the immune system was reading, and either tolerating or rejecting, was sugar chemistry on the surfaces of cells.

The medical world essentially ignored the result. Surgeons continued to transfuse blood without typing it, and patients continued to die at roughly the same rate, until 1907, when an obstetrician at Mount Sinai Hospital in New York named Reuben Ottenberg performed the first deliberately matched transfusion, having read Landsteiner's paper. Ottenberg used the technique on hundreds of patients over the next several years and almost never lost one. By the First World War the British and French and Americans were typing blood at field hospitals; by the second, the typing was being done in the back of a moving ambulance. Tens of millions of lives have now been saved by Landsteiner's footnote. He was awarded the Nobel Prize in Physiology or Medicine in 1930.

The discovery did something quieter than save lives. It announced that the outside of a cell was not a featureless membrane. The cell was wearing a fingerprint.

The fingerprint is made of sugars. Not the kind that sweeten coffee. They are short chains of saccharide molecules called glycans, anywhere from one to a few dozen units long, attached to the proteins and the lipids of the cell membrane. Together they form a dense forest called the glycocalyx, three to five hundred nanometres thick, that every animal cell wears on its outer surface. Every cell type in the human body wears a slightly different glycocalyx, and the glycocalyx of any given cell changes as the cell's situation changes. Cancer cells re-pattern their glycans as they become malignant. Immune cells re-pattern theirs when they are activated. Stem cells re-pattern theirs as they differentiate. The information was always there. We could not read it.

This month, in Nature Nanotechnology, a team led by Leonhard Möckl at the Max Planck Institute for the Science of Light in Erlangen has reported the first method that can. It is called Glycan Atlasing. The technique stitches together two ideas. First, the team designs DNA-tagged lectins, sugar-binding proteins from plants and bacteria each of which recognises a specific glycan structure, and uses them as labels. Second, they pair the labels with metabolic oligosaccharide engineering, a technique that feeds the living cell sugars with small chemical handles attached, so that the cell incorporates the handles into its own glycocalyx as it grows. Together, the two techniques let the researchers see, under a super-resolution microscope, the actual position of every recognisable sugar on the surface of a cell at a resolution of a few nanometres.

The result is an atlas. They have mapped the glycocalyx of dozens of cell types from across the human body and shown that the spatial pattern of sugars, not just which sugars are there, reliably tracks what the cell is doing. Cancer cells from a breast tumour rearrange their surface sugars in ways that distinguish them clearly from the surrounding healthy tissue, even before the cells have started to multiply detectably. Activated immune cells re-pattern their surface within hours of seeing a pathogen. The Möckl group is now working with two German university hospitals on whether a routine blood sample, run through the Glycan Atlasing pipeline, could detect early-stage cancers that would otherwise not be visible for years.

If the technique scales, the medical implications are quietly enormous. Cancer detected from a blood sample is cancer that surgery can still cure. The Möckl paper is not yet that test; it is the proof that the test is possible.

What it adds to the longer story is what Landsteiner added in 1900. The sugars on the surfaces of cells are how cells talk about themselves. The body has been carrying a chemical fingerprint, on every cell of every tissue, since before there were doctors to ask about it. Landsteiner found four patterns and saved tens of millions of lives. Möckl's team has now mapped thousands. The patterns were there the whole time.

There is a quiet sentence at the end of Möckl's paper that is worth quoting. The authors write that the glycocalyx, even with the new instruments, is still a long way from being completely characterised. They write that they have produced an atlas, not a map. There is a difference. An atlas shows where the major regions are; a map shows what is in them. Landsteiner produced an atlas in 1900. The next twenty years filled it in. The same will be true of this one.

The sugars were doing the talking the whole time. We are only now beginning to write down what they said.

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STEM 1900 to 1930, the Institute of Pathological Anatomy in Vienna, Mount Sinai Hospital in New York, and the Karolinska Institutet in Stockholm A May 2026 Nature Nanotechnology paper by Möckl and colleagues at the Max Planck Institute for the Science of Light in Erlangen introduces Glycan Atlasing, a technique that combines DNA-tagged lectins, metabolic oligosaccharide engineering and super-resolution microscopy to map every glycan on the surface of a cell at nanometre resolution; the technique distinguishes cancerous from healthy tissue and tracks immune-cell activation by the spatial pattern of sugars alone.

Sources & Verification (12 claims checked, 6 searches)

Karl Landsteiner (1868-1943) was an Austrian physician who worked at the Institute of Pathological Anatomy at the University of Vienna; he was 32 years old in late 1900 when he carried out the experiments that led to the identification of the ABO blood groups.

en.wikipedia.org — "Karl Landsteiner (14 June 1868 - 26 June 1943) was an Austrian-born American biologist, physician, and immunologist. He "

In 1900, Landsteiner separated red blood cells from serum from samples taken from himself and his laboratory colleagues, mixed every serum with every set of cells, and observed that some combinations caused the red cells to clump (agglutinate) while others did not, identifying three blood groups he initially called A, B and C (the C group was later relabelled O).

embryo.asu.edu — "He started testing the sera and red blood cells of the scientists who worked in his laboratory in 1900 and found that th"

Landsteiner's initial 1900 report of the observation appeared as a footnote in his paper 'Zur Kenntnis der antifermentativen, lytischen und agglutinierenden Wirkungen des Blutserums und der Lymphe', published in Zentralblatt für Bakteriologie; his full description of the three blood groups followed in 1901 in the Wiener klinische Wochenschrift under the title 'Ueber Agglutinationserscheinungen normalen menschlichen Blutes'.

embryo.asu.edu — "Landsteiner relegated his observation of agglutination to a footnote in a paper he wrote in 1900, published in Zentralbl"

The fourth blood group, AB, was identified in 1902 by Alfred von Decastello and Adriano Sturli, both working in the same Vienna laboratory under Landsteiner.

en.wikipedia.org — "In 1902 Alfred von Decastello and Adriano Sturli, working under Landsteiner at the Vienna laboratory, identified the fou"

The ABO antigens that determine blood-group compatibility are sugar moieties (terminal saccharides such as N-acetylgalactosamine and galactose) attached to glycoprotein and glycolipid chains on the surface of red blood cells; the immune system distinguishes self from non-self by these sugars.

en.wikipedia.org — "The ABO blood group antigens are sugar (carbohydrate) molecules attached to glycoproteins and glycolipids on the surface"

Before the introduction of ABO matching, blood transfusions resulted in fatal haemolytic reactions in a substantial fraction of recipients; clinical adoption of Landsteiner's typing system began with Reuben Ottenberg's first deliberately matched transfusions at Mount Sinai Hospital in New York in 1907.

en.wikipedia.org — "Before the 1900s, blood transfusions had a high mortality rate due to incompatibility reactions. In 1907, Reuben Ottenbe"

Karl Landsteiner was awarded the Nobel Prize in Physiology or Medicine in 1930 for his discovery of the human blood groups.

www.nobelprize.org — "The Nobel Prize in Physiology or Medicine 1930 was awarded to Karl Landsteiner 'for his discovery of human blood groups'"

Every animal cell wears an outer coat of branched sugar polymers called the glycocalyx, attached to membrane proteins and lipids; the glycocalyx is approximately 100 to 500 nanometres thick and changes in composition and arrangement as the cell's state changes.

en.wikipedia.org — "The glycocalyx is a glycoprotein-polysaccharide covering surrounding the cell membranes of bacteria, epithelial cells an"

In May 2026, a team led by Leonhard Möckl at the Max Planck Institute for the Science of Light in Erlangen published 'Glycan atlassing enables functional tracing of cell state' in Nature Nanotechnology, introducing the technique they call Glycan Atlasing.

www.nature.com — "Glycan atlassing enables functional tracing of cell state. Authors: Dijo Moonnukandathil Joseph, Nazlican Yurekli, Sarah"

The Glycan Atlasing technique combines DNA-tagged lectins (sugar-binding proteins each of which recognises a specific glycan structure) with metabolic oligosaccharide engineering (feeding live cells modified sugars with chemical handles), and uses super-resolution microscopy to map the position of individual glycans on the cell surface at nanometre resolution.

phys.org — "The Möckl group's Glycan Atlasing combines DNA-tagged lectin labelling with metabolic oligosaccharide engineering, and u"

The Möckl team's findings show that the nanoscale spatial arrangement of glycans (not just which glycans are present) reliably tracks the functional state of the cell, including immune-cell activation and the transition from healthy to cancerous tissue.

www.sciencedaily.com — "Immune cells changed their sugar layouts when activated, and cancerous tissues displayed distinct surface signatures com"

The Möckl group has begun work with collaborating German university hospitals on whether routine blood samples processed through the Glycan Atlasing pipeline could be used for early detection of cancers that would otherwise be invisible to conventional screening.

www.republicworld.com — "The Max Planck team is now collaborating with German university hospitals to test whether the Glycan Atlasing pipeline c"