CHARACTERIZATION OF SELF-GLUTAMIC ACID DECARBOXYLASE 65-REACTIVE CD4(-CELL CLONES ESTABLISHED FROM JAPANESE PATIENTS WITH INSULIN-DEPENDENTDIABETES-MELLITUS() T)

To investigate autoimmunity to glutamic acid decarboxylase (GAD) 65 in Japanese patients with insulin-dependent diabetes mellitus (IDDM: typ e I diabetes), we established seven CD4(+) T-cell clones, by stimulati ng peripheral blood mononuclear cells (PBMC) of six IDDM patients, usi ng a mixture of overlapping human GAD65 peptides. No GAD65 autoreactiv e T-cell clones were evidenced in four healthy controls. Specificities of T-cell clones were as follows: (a) two clones specific to GAD65 p1 11-131 (residue 111 to 131) + DR53 (DRB40103); (b) one clone specific to GAD65 p413-433 + DR1 (DRB10101); (c) two clones specific to GAD65 p200-217 + either DR9 (DRB10901) or DR8 (DRB1*0802); and (d) two clo nes specific to GAD65 p368-388 + DP2 (DPA101 or 0201-DPB1*0201). Two DR53-restricted and one DR1-restricted T-cell clones,responded to a re combinant human GAD65 protein, and showed cytotoxicity against B lymph oblastoid cell lines pre-pulsed with the peptides. Six T-cell clones e xhibited the Th1-like phenotype. Interestingly DR53-restricted T-cell clones killed a Fas-deficient B lymphoblastoid cell line, thereby indi cating that cytotoxicity was not completely dependent on a Fas-Fas Lig and interaction. Thus, the T-cell epitopes were mapped in a limited po rtion of GAD65 protein, with a tendency to be restricted by disease-as sociated HLA-DR,but not DQ molecules. (C) American Society for Histoco mpatibility and Immunogenetics, 1998. Published by Elsevier Science In c.