Developmental Immunotoxicology of Di-(2-Ethylhexyl)phthalate (DEHP): Age-Based Assessment in the Female Rat

Di-(2-ethylhexyl)phthalate (DEHP) helps provide flexibility to plastic products including food containers and medical IV devices. Age-based sensitivity to DEHP-induced immunotoxicity was compared in female CD strain rats following administration for 16 consecutive days in utero vs. adult exposure. Pregnant and non-pregnant rats received 0, 37.5, 75, 150, or 300 mg/kg/day of DEHP in soybean oil daily by oral gavage. In pregnant animals, this corresponded to days 6-21 of gestation. In exposed offspring, anogenital distance (AGD) was measured at one and three weeks of age. For a subset of offspring, immune assessment was conducted at 5 weeks of age following KLH immunization at 3 and 4 weeks. KLH immunizations occurred in remaining offspring at 11 and 12 weeks with immune assessment at 13 weeks. Nonpregnant adults were immunized concurrently with adult offspring and underwent immune assessment 13 weeks post-DEHP exposure. Litter size, sex ratio, and 1-week body weights were unaffected by treatment. However, AGD was altered at both ages assessed. Three-week (but not 5-week) body weights were elevated in exposed offspring. Immune organ weights, thymus histology, antibody levels (IgG and IgE), DTH reaction to KLH, total and differential leukocyte counts, ex vivo cytokine production (IL-2, -4, -10, -12, interferon-gamma), as well as TNF-alpha and nitric oxide production by macrophages were not altered by treatment at any age. Flow cytometry analysis of splenocytes showed no differences during the juvenile assessment. In conclusion, in utero exposure of female rats to DEHP alters some developmental parameters (i.e., AGD) but has no persistent effect on the immune system based on the assessment parameters. Adult female rats also had no detectable immune alteration following similar exposures.