A composition is described that comprises a treatment effective amount of cells, of which a portion are T-cells, wherein the T-cells have been harvested from cell culture and are thereby removed from activating stimuli in the culture and the harvested T-cells are formulated for infusion by a method comprising (1) contacting the T-cells with one or more agents that ligate a cell surface moiety on at least a portion of the T-cells, (2) cross-linking the one or more agents with biodegradable nanospheres or microspheres coated with a material capable of cross-linking the one or more agents, (3) suspending the T-cells, the one or more agents and the coated biodegradable nanospheres or microspheres in an infusion medium, and (4) packaging in a suitable container, wherein the T-cells are in an activated state in the medium, wherein the one or more agents are mouse-derived monoclonal antibodies, or fragments or genetically engineered derivatives thereof, and the material coating the nanospheres or microspheres is goat or sheep anti-mouse polyclonal antibodies. Methods for the preparation of the composition are also described.