Understanding unconventional T cell development to generate an ‘off the shelf’ immunotherapy to treat human diseases 2226160

Introduction Unconventional T cells represent more than 10% of total T cells within the blood and tissues of humans and play critical roles in cancer and infection. Human unconventional T cells exhibit dual effector functions; they rapidly secrete cytokines upon stimulation, and they express granzymes and perforin that enables them to lyse infected or cancerous cells. Methods Here, we studied the development of unconventional T cells isolated from the postnatal human thymus and from artificial thymus organoids, tracking changes in development using flow cytometry, RNA-sequencing, precursor-product experiments and cytokine expression. Results Our research has deciphered how unconventional T cell subsets including MAIT cells, γδ T cells and NKT cells develop in the human thymus. We reveal that all three subsets develop via a linear pathway defined by the upregulation of the transcription factor PLZF and the Killer cell lectin-like receptor subfamily B, member 1 (CD161). Further, functional programming of unconventional T cells takes place in the human thymus. We demonstrate that the development of unconventional T cells can be faithfully reproduced using artificial thymus organoids, which allows for detailed interrogation of this process by removal of key factors that influence their development. Furthermore, we demonstrate that our unconventional T cells can be developed as an “off the shelf’ immunotherapy. Conclusion Collectively, our work reveals how understanding unconventional T cell development in the human thymus has led to new opportunities to utilize these cells to treat human diseases such as cancer or microbial resistant infections. Funding Source NHMRC Topic Categories Translational and Interventional Immunology (TI)