Maternal prolactin composition can permanently affect epidermal γδT cell function in the offspring

There have been few studies aimed at determining the effects of maternal peptide hormones on the developing fetus and even fewer aimed at determining the long-term consequences of abnormalities in maternal hormone exposure. In this study, we have examined the effect of maternal prolactin (PRL) on the production, seeding and long-term function of a T lymphocyte subset for which the precursors are only present during fetal life. Using this system, we can determine long-term consequences of maternal hormone exposure without concern for the subsequent influence of the offspring's endocrine milieu. Recombinant versions of the two major forms of the pituitary hormone, PRL, were administered to rats throughout pregnancy. Administration of a molecular mimic of phosphorylated PRL (PP-PRL) resulted in a marked increase in the level of apoptosis in the thymus of newborn pups, an effect that was not duplicated by administration of unmodified PRL. The increased thymic apoptosis in the animals exposed to PP-PRL resulted in decreased epidermal seeding of gammadeltaT cells and a markedly decreased gammadeltaT cell-modulated epidermal response in the offspring. This decreased gammadeltaT cell modulated response persisted to adulthood. We conclude that maternal PRL composition during pregnancy can have a permanent effect on at least one component of the developing immune system.