Endocrine Abstracts

Introduction: Type 1 Diabetes Mellitus (T1DM) causes autoimmune destruction of insulin producing b-cells, affecting approximately 8.4 million individuals worldwide. Autologous stem cell derived b cell (sc-b cell) transplantation is a promising treatment, however receipient immunological responses remain a challenge. This pilot study utilised mass cytometry (CyTOF) to assess immune responses in co-cultures of peripheral blood mononuclear cells (PBMC) with autologous sc-b cells from T1DM patients.

Methods: PBMCs were isolated from three T1DM donors at two time points one year apart, and co-cultured with sc-b cells differentiated from each donor’s stem cells. For each donor, the positive stimulation control was phorbol 1-myristate 13-acetate (PMA), while the negative control was sc-a or progenitor cells. Post-incubation, samples were labelled with metal conjugated antibodies for CyTOF analysis. Manual gating and unsupervised clustering models were used to identify immune subsets.

Results: The relative proportions of CD4 and CD8 T-cell subsets (naïve, memory) were similar with each stimulation condition, whilst differing across individuals. Notably, donor 1 had a higher proportion of memory CD8 T-cell subsets. The immunological response of PMA stimulation was different from the response to co-culturing with sc-b or sc-a cells. T-cell cytokines abudances, IFNg and granzyme B, were elevated in response to all stimulation conditions. However, abundance of CD25, CD137, and PD-1, in naïve and memory CD4 and CD8 T-cells, were higher in PBMCs co-cultured with sc-b or sc-a than when treated with PMA.

Conclusion: This pilot study demonstrated highly individualized immune profiles, further highlighting the immunological heterogeneity within T1DM patients. Within this small donor subset, no specific immune signatures were identified that indicated an autoreactive response to sc-b cells. Further research should aim to study responses in a larger donor subset and assess the clinical correlates of these immune signatures, which could have practical implications for T1DM prevention and treatment.