LAUSR

Lanthanum, a major rare earth element, can exert detrimental effects on the adult immune system, but its developmental immunotoxicity (DIT) remains obscure. This study was designed to evaluate the DIT of lanthanum nitrate (LN) and the self-recovery of LN-induced DIT 21 days following cessation of exposure. BALB/c pregnant dams were exposed to 0, 0.1, 1, and 10 mg/kg body weight/day LN by gavage during gestation and lactation. Results showed that in male offspring, LN markedly inhibited the adaptive immunity at postanal day 21 (PND21) and the inhibitory effect on cellular immunity continued to PND42 (after three weeks of self-recovery). In female offspring, LN suppressed cellular immunity at both PND21 and PND42. Moreover, decreased relative organ weight of thymus, humoral immunity and proportion of double-positive T cells in thymus were also observed at PND42. Bcl-xl protein level decreased in thymus of female at PND42, while the level of β-catenin increased. These changes might contribute to accelerating the degeneration and weight loss of thymus. Overall, in-utero and postanal exposure to LN could induce impairments of immunity in offspring, especially the female, and adaptive immunosuppression would persist throughout development into adulthood. The LOAEL of LN for DIT should be 1 mg/kg.