DEVELOPMENT AND FUNCTION OF T-CELLS IN MICE RENDERED INTERLEUKIN-2 DEFICIENT BY GENE TARGETING

INTERLEUKIN-2 (IL-2) is a lymphocytotropic hormone which is thought to have a key role in the immune response of mammalian cells. It is produced by a subpopulation of activated T-lymphocytes and acts in vitro as the principal auto- and paracrine T-cell growth factor (for reviews see refs 1-3). IL-2 is, however, not the sole T-cell growth factor 4,5, nor does it act exclusively on T cells, also promoting growth of NK cells 6 and differentiation of B cells 7. A role for IL-2 in T-cell development has been postulated but remains controversial 8-12. Here we test the requirement for IL using IL-2-deficient mice generated by targeted recombination. We find that mice homozygous for the IL-2 gene mutation are normal with regard to thymocyte and peripheral T-cell subset composition, but that a dysregulation of the immune system is manifested by reduced polyclonal in vitro T-cell responses and by dramatic changes in the isotype levels of serum immunoglobulins.