Jan D. Bos 1951-2020

Jan D. Bos was born in Leiden (The Netherlands) in 1951 and studied medicine in Rotterdam. He was appointed to the Chair of the Department of Dermatology at the Academic Medical Center (AMC) University of Amsterdam in 1990. Jan Bos was the successor of Prof. Rudi Cormane who had died unexpectedly in 1987 at the age of 62 years. Jan Bos was trained by Rudi Cormane, who was also the promoter of his thesis entitled ‘Immunological aspects of syphilis’(1981). Jan Bos was heavily influenced by Rudi Cormane and it was thus not surprising that he developed a strong interest in the immunology of the skin. After his residency he became head of the department of Clinical Immunology and Allergology and together with the departments of Cell Biology and Histology and Pathology focused his research on the immunophenotyping of both normal and lesional skin especially psoriasis. These first immunohistological studies demonstrated the importance of T lymphocytes and their subsets in psoriasis. This understanding coincided with the discovery of monoclonal antibodies for the detection of T-cell subsets. At the same time the T-cell selective immunosuppressant cyclosporine was successfully introduced for the treatment of psoriasis, thereby underlining the pivotal role of activated T cells in this skin disease. All these developments lead to the concept of the skin immune system that was published in 1986 by Bos and Kapsenberg as a review in Immunology Today. The term ‘Skin Immune System’ (SIS) summarized the whole complexity of the immune system of the skin, both at a cellular level and a humoral level. In 1990 this SIS concept was presented in a textbook edited by Jan Bos . In this book the present state of knowledge of especially the immunophysiology of the integument was placed centrally. The success of this book was demonstrated by the fact that two further editions were published (1997 and 2005). In these books the pure description of many humoral and cellular constituents of the skin were brought together in both normal and diseased skin. Throughout his career Jan Bos continued to work on psoriasis, both on the preclinical and clinical aspects. In the late 1990s Jan shifted his attention to atopic dermatitis.
 
During his career Jan Bos became an honorary member of the Polish (1991), Hungarian (1992), Scottish (1996), and German (2001) Dermatological Societies. He was appointed Fellow of the Royal College of Physicians Edinburgh (FRCP Edin) and the Royal College of Physicians London (FRCP), and Doctor Honoris Causa (University of Szeged, Hungary). In addition to Visiting Professorships (University of Michigan and Massachusetts Medical School) he received several national and international prizes. He was very successful in stimulating PhD students; more than 50 PhD students finished their thesis under his guidance.
 
Jan Bos was a special man, sometimes unpredictable and outspoken. Nevertheless he could also be extremely charming and he helped a lot of people with their careers. Jan was very proud of his two sons. In 2009 he developed a lymphoma and in the same year his first wife died from cancer. These events affected Jan very much and in May 2011 he stepped down as chair of the Department of Dermatology of the AMC. In 2013 Jan re-married. Because of his weak health Jan avoided public appearances, his last one being in 2016 when he received the Chanfleury van IJsselsteijn award during the annual Dutch dermatology meeting in Amsterdam. Jan died on the 22nd of January 2020 in his own AMC hospital after a short illness.
 
Prof. Menno A. de Rie