Fig. 1.

Experimental approach. (a) Pancreatic islets were isolated and handpicked from two NOD.β2m^null.HHD mice, expressing human leucocyte antigen (HLA)-A*0201, but no murine class I molecules, yielding a population of highly pure islets (b, stained with dithizone). These islets were cultured for 7 days in the presence of interleukin (IL)-2, harvested and used as responders in an interferon (IFN)-γ enzyme-linked immunospot ELISPOT (assay). Class II major histocompatibility complex (MHC) antigen-negative, transporter antigen processing (TAP)-deficient T2 cells were used as antigen-presenting cells (APC). These cells express low levels of class I MHC molecules, which are increased and stabilized upon binding of exogenous peptides. (c) Flow cytometry reveals that a subset of highly activated CD8 T cells was expanded. Data are from a single preparatory experiment performed prior to and independent of the seven experimental runs to screen the peptide library.