Unmodified and phosphorylated prolactin and gamma delta T cell development and function

This manuscript discusses our studies to date concerning the effects of unmodified prolactin (PRL) and phosphorylated PRL on immune function. Most of the discussion refers to effects of changing the ratio of these two forms in maternal PRL on gamma delta T cell development in rat pups in utero, but limited experiments where adult animals have been directly treated are also discussed. The manuscript begins with some general background on gamma delta T cells and the different forms of PRL and then proceeds to a discussion of experimental findings. Results demonstrate that the ratio of unmodified to phosphorylated PRL during rat pregnancy is crucial to normal epidermal gamma delta T cell development in the pup thymus. Elevation of phosphorylated PRL in the dams, by administration of a recombinant molecular mimic of phosphorylated PRL, produces a defect in epidermalgamma delta T cell seeding and subsequent function in the offspring. In contrast, a functional defect is not seen for uterine gamma delta T cells in the offspring, a finding likely reflective of the continued availability of precursors to these cells after the fetal period. Preliminary results from treatment of the NZB/NZW mouse model of lupus with the two forms of PRL suggest opposing effects of unmodified and phosphorylated PRL on one measure of the disease.