Cytokines and T cells in host defense.

Soluble and cell-bound ligands profoundly influence the differentiative fate of lymphocytes during an immune response. Recent advances have been made in understanding the role of cytokine signals and costimulatory signals in the regulation of T cell responses associated with resistance or susceptibility to infection. There has also been recent progress in defining the requirements for the generation and maintenance of immunologic memory, a critical component of adaptive immunity.