Nanoparticle-based modulation of CD4 + T cell effector and helper functions enhances adoptive immunotherapy.

Helper (CD4 + ) T cells perform direct therapeutic functions and augment responses of cells such as cytotoxic (CD8 + ) T cells against a wide variety of diseases and pathogens. Nevertheless, inefficient synthetic technologies for expansion of antigen-specific CD4 + T cells hinders consistency and scalability of CD4 +  T cell-based therapies, and complicates mechanistic studies. Here we describe a nanoparticle platform for ex vivo CD4 +  T cell culture that mimics antigen presenting cells (APC) through display of major histocompatibility class II (MHC II) molecules. When combined with soluble co-stimulation signals, MHC II artificial APCs (aAPCs) expand cognate murine CD4 + T cells, including rare endogenous subsets, to induce potent effector functions in vitro and in vivo. Moreover, MHC II aAPCs provide help signals that enhance antitumor function of aAPC-activated CD8 + T cells in a mouse tumor model. Lastly, human leukocyte antigen class II-based aAPCs expand rare subsets of functional, antigen-specific human CD4 + T cells. Overall, MHC II aAPCs provide a promising approach for harnessing targeted CD4 +  T cell responses.