Provided are methods of enhancing ex vivo proliferation of a T cell population, the methods comprising contacting the T cell population with IL-7 and anti-CD3/CD28 antibody to activate and expand the T cell population. Further provided are methods of generating an antigen-specific cytotoxic T cell population comprising priming a CD3/CD28-expanded T cell population against an antigen (e.g., a cancer cell) in the presence of at least one of IL-7, IL-12, and IL-15, or a combination thereof. Further provided are methods of treating T cell lymphopenia in a subject, comprising administering a CD3/CD28-expanded T cell population to the subject.