Unveiling Diabetes - Historical Milestones in Diabetology. Группа авторов

Fig. 4. From the publication “About the Nerves of the Skin,” 1868 [2, 9].

      Since then, a slew of publications has tried to unveil the functions of these cells which migrate throughout the body. Generally, dendritic cells take care of the capture, uptake, and processing of antigens. They play an important role in the process of infection, for example, with HIV or HPV viruses. Langerhans cells also contain langerin – a protein of importance in immune mechanisms. Langerin, on mucosal Langerhans cells of the human genital epithelium, binds to HIV-1 and subsequently internalizes it into Birbeck granules to be degraded.

After this intermission, Paul returned to work on his thesis. He described nine types of cells in the pancreas. The ninth group of cells he labeled as being small, quite homogenous cells which are located together in small groups (Zellhäufchen). At the end of the short description of these cells he stated that he has no clue about their function (Fig. 5). Initially it had been his intention to continue his work with experiments on the function of the pancreas but he found that it was technically impossible for him to study the function of the pancreas without being able to keep rabbits he was using alive, even for a while. Only 20 years later, Minkowski and von Mering managed to perform a pancreatectomy in dogs while also being able to keep them alive. It is, by the way, astonishing that nobody before Langerhans had the idea to inject vermilion or any other color into the aorta before studying the histology of the pancreas.

      After his doctorate, Langerhans had no further dealings with the pancreas and the cell clusters he described went unnoticed. That was, of course, until Prof. Édouard Laguesse, in Lille, became aware of the peculiar islands in the pancreas again. It is, in itself, curious that Laguesse even had knowledge of Langerhans’ doctoral thesis. Only 150 copies were ever printed and the vast majority of them were to be found in German Universities. Today, only very few copies have survived; Björn Hausen found only 8 original copies worldwide.

At a meeting of the biological society in Paris in 1893, Laguesse reported on the peculiar structures in the pancreas and called them ilôts de Langerhans [1, 3]. Laguesse had already previously expressed the hypothesis that there were two forms of diabetes and that one of these had something to do with the pancreas.

      It is very surprising that the doctoral thesis does not contain a single drawing – in contrast to the publication on the Langerhans cells of the skin. Paul was by no means lacking a talent for drawing. He was a very capable draughtsman and painter, a talent he shared with another renowned discoverer in diabetology, Frederik Banting.

      However, Paul’s “godfather” Rudolf Virchow must not have been entirely satisfied with the thesis. The grade given for this doctoral thesis was moderate, although the work is dedicated to him “in reverence and gratitude.” Also, in his rigorosum Paul receives the worst grade of the three evaluating professors from Prof. Virchow – sufficient.

      On March 18 Paul Langerhans received his certificate of passing the medical examination. Initially he continued to work in Prof. Virchow’s laboratory together with his lifelong best friend Friedrich Albin Hoffmann. Hoffmann wrote in his autobiography about Langerhans: “His winning nature and his great diligence made him very pleasant to me. We had lunch together at Töpfer’s hotel (just in front of the Charité hospital in Karlsr. 7), discussed what we were working on and what interesting sections Virchow had. Soon he took me with him to his parents’ house, where his father, his stepmother and his sister were most kind to me. I soon felt very comfortable in this entourage.” We also know from Hoffmann that Paul did not belong to any student fraternity, which was extremely unusual in German academic circles in the 19th century where it was practically obligatory.