Prolactin as a second messenger for interleukin 2.

The generation of an effective immune response requires the selection and proliferation of antigen-specific lymphocytes. Activation of at least some T lymphocytes involves the sequential stimulation of cell surface receptors, including the T-cell receptor for antigen, the interleukin 2 receptor, and the prolactin receptor. Prolactin signaling in T lymphocytes appears to utilize a classical receptor-mediated kinase cascade and a novel peptide hormone activation pathway involving nuclear translocation.