Abstract: This invention relates to cellular-based therapies for increasing the level of regulatory T cells (Treg) and/or decreasing the level of pro-inflammatory T cells (Th17) to induce anergy or immune tolerance. To provide these therapeutic effects, two allogeneic leukocyte populations are contacted (in vivo, in vitro or ex vivo) and one of these leukocyte population is modified to bear on its surface a low-immunogenic biocompatible polymer so as to prevent pro-inflammatory allo-recognition. Cellular-based preparations and processes for achieving cellular therapy are also provided.