Paul Langerhans (1847 – 1888) – whose face is depicted in the logo of the German Center for Diabetes Research (DZD) – is the discoverer (1869) of the islets of Langerhans in the pancreas, which were later named after him. These cell clusters are also referred to as Langerhans islets or islet cells and often collectively as islet organ. Since among other functions these cells produce and secrete insulin, they are of great importance for diabetes research.

Paul Langerhans was born on July 25, 1847 in Berlin as son of the physician Paul Langerhans (1820 – 1909) and his wife Anna, born Keibel. He graduated first in his class from school (Abitur 1865) and demonstrated a special interest in science. In 1867, as a student in Berlin, he began his studies on the pancreas under the supervision of Rudolf Virchow.

Microscopic anatomy of the pancreas
Virchow suspected “that this gland, too, not only secreted outwardly but also inwardly into the blood”, i.e. that it was endocrine-active. Langerhans’ studies confirmed this, but he was unable to make further observations about the secretory processes as such. “Due to the total lack of suitable devices to study a rabbit pancreas with a tolerable prospect of sustaining life for a lengthy period, I had to refrain from studying such a favorable object from the very beginning.”
In his “Contributions on the microscopic anatomy of the pancreas” Langerhans described nine different cell types and describes one of these groups as follows: “… small cells of almost perfect homogeneous content and of a polygonal form, with round nuclei without nucleoli, mostly lying together in pairs or small groups.” The significance of insulin, which was secreted by these cell groups, was not recognized until 1921 by Frederick Banting and Charles Best. The cell clusters first described by Langerhans were rediscovered 16 years later by Gustave Edouard Laguesse in his pancreas studies, and in 1893 they were named “ilôts de Langerhans” after their discoverer in a meeting of the Biological Society of Paris.
Although Langerhans himself did not continue research on the pancreas, he discussed the topic in many letters to colleagues and suggested that more attention should be paid to this organ.

Associate professor
Langerhans received his doctorate in 1869 with the dissertation “On contributions to the pathological anatomy of the pancreas”. In the Franco-Prussian War he served as a military doctor at the front lines.
In an accelerated procedure, he submitted his Habilitation thesis in October 1871 to the University of Freiburg, where he received the coveted position of leading dissector and was appointed lecturer (Privatdozent). In 1873 he became Associate Professor of Pathology and Anatomy at the Faculty of Medicine in Freiburg.

Dermatological studies
While still a student, Langerhans conducted studies on the nerve endings in the skin. More than a hundred years later it was discovered that the Langerhans cells (dendritic cells) in the epidermis are immunocompetent cells which play an important role in many skin diseases. The Langerhans granular layer of the skin remained associated with his name up into the 20th century, until the dermatological term stratum granulosum became common.

Tuberculosis patient and physician
In 1874 Langerhans was diagnosed with pulmonary tuberculosis and subsequently moved to Capri. He then resigned from his professorship in Freiburg in order to spend his last years on the island of Madeira. In 1879 he opened a practice for tuberculosis patients in the city center. He also conducted marine biological studies, which are also associated with his name.
Paul Langerhans died on July 20, 1888 in Quinta Lambert, the current seat of the governor of Madeira. A bust of Paul Langerhans was erected in his honor on the campus of the Charité in Berlin in October 2012.

This information on the life and work of Paul Langerhans was taken from the book Die Inseln des Paul Langerhans. Eine Biographie in Bildern und Dokumenten [The Islets of Paul Langerhans. A biography in pictures and documents (in German only)] by Björn M. Hausen.