An in vitro method for the obtention of a food- or auto-antigen specific Tr1 cell population from a leukocyte or a PBMC population, includes stimulating the PBMC or leukocyte population with the food- or auto-antigen, and recovering the food- or auto-antigen specific Tr1 cell population from the stimulated cell population. Preferably, the PBMC or leukocyte population is re-stimulated at least once with the same antigen after step (1), in the presence of IL-2 and at least one interleukin selected from the group consisting of IL-4 and IL-13. The in vitro method may further include a third step of expanding the recovered antigen-specific Tr1 cell population, advantageously by contacting them with feeder cells capable of expressing factors necessary for the expansion. Preferably, the feeder cells are recombinant insect feeder cells.