Sebastiaan Heidt started working in the field of organ transplantation and immunogenetics in 2003 when he began his PhD studies in the laboratory of Prof. Dr. Frans Claas at the Department of Immunohaematology and Blood Transfusion of the Leiden University Medical Center.
In 2009, he defended his thesis, after which his first post-doctoral position was in the laboratory of Prof. Dr. Kathryn Wood at the Nuffield Department of Surgery of the University of Oxford. In 2011, he returned to Leiden to continue working with Prof Dr. Frans Claas as a Senior Scientist. From this moment onwards, hands-on working in the laboratory became less frequent, and he started to be involved in the supervision of PhD students and overseeing several research projects.

In 2014, he was offered a position as Assistant Professor and Managing Director of the Eurotransplant Reference Laboratory (ETRL), which is also situated in the Department of Immunohaematology and Blood Transfusion of the Leiden University Medical Center. As a representative of the ETRL, he became a member of the Dutch HLA Working Party, as well as the secretary of the Eurotransplant Tissue Typing Advisory Committee. In the meantime, Sebastiaan became increasingly active several scientific societies, first by joining the EFI Scientific Committee in 2015, by becoming Editor-in-Chief of the EFI Newsletter in 2017, and by being one of the founding members of the ASHI Science and Technology Initiatives Committee in 2017. In addition, he is Section Editor solid organ transplantation of HLA, the house journal of EFI. Furthermore, Sebastiaan is actively involved in the epitope compartment of the current 17th workshop.

From October 2017, Sebastiaan has taken over responsibility over the complete research program of Transplantation Immunology group after Prof. Dr. Frans Claas’s retirement. The current projects studied in the laboratory are the immunogenicity and antigenicity of B cell epitopes on HLA molecules, HLA-specific B cell memory, HLA antibody characteristics, immune monitoring of transplant recipients, and reproductive immunology.