no. 553142; BD Pharmingen, Becton Dickinson, San Jose, CA, USA). Staining was carried out in 5H buffer to detect H-2Db (expressed on NOD, C57BL/6J and CByB6F1/J lymphocytes) and H-2Kb– (C57BL/6J and CByB6F1/J mice) using the following antibodies: α-H-2Db-phycoerythrin

(PE) (clone KH95, cat. no. 111507; BioLegend, Inc., San Diego, CA, USA), α-H-2Kb-AlexaFluor 647 (cat. no. 116511, clone AF6-88.5; BioLegend), α-CD4-Horizon (cat. no. 48-0042-82, clone RM4-5; eBioscience, Inc., San Diego, CA, USA), α-CD8α-biotin (cat. no. 13-0081-82, clone 53-6.7; eBioscience) in combination with streptavidin–AlexaFluor 488 (cat. no. S32354; Molecular Probes, Invitrogen). 7-Aminoactinomycin D (7AAD) (cat. no. 559925; BD Pharmingen, Becton Dickinson) was BTK inhibitor order used for live/dead cell discrimination. Diabetes-free survivals in the experimental groups were assessed by Kaplan–Meier analysis and comparisons between groups were calculated using the

log-rank test. From groups B1, B2 and C2, the three mice that did not deliver a litter were excluded from the analyses. Multivariate analysis of diabetes outcome was performed using the Cox proportional hazards model, which included the covariates mating group and insulin autoantibody Rucaparib titre at the time of mating. Comparisons of insulin autoantibody titres between group A1 and C1 were made using Student’s t-test. Two-tailed P-values of < 0·05 were considered significant. For all statistical methods, PASW statistics version 18 (SPSS, Chicago, IL, USA) was used. Mating at age 10 weeks did not accelerate diabetes, but resulted in a significant delay of diabetes development in the NOD dams (unmated females, 81% diabetes by age 28 weeks, mated females, 60% by age 28 weeks; P = 0·04; Fig. 1a). Differences were observed between mating partners. Mating at 10 weeks with NOD males had no effect on diabetes incidence (71%

by age 28 weeks, P = 0·38), whereas mating with MHC haploidentical CByB6F1/J male mice had the strongest Tideglusib effect on diabetes development (38% by age 28 weeks, P = 0·01 versus unmated NOD females; P = 0·08 versus NOD male mated females). Mating with fully MHC mismatched C57BL/6J males did not delay diabetes significantly (73% by age 28 weeks, P = 0·22 versus unmated females). Mating at age 13 weeks did not affect diabetes development significantly in NOD females (unmated females, 94% diabetes by age 28 weeks, mated females, 72% by age 28 weeks; P = 0·22; Fig. 1c) although, again, diabetes development was lowest in females mated with CByB6F1/J male mice (64% by age 28 weeks, P = 0·13).