Immunotoxicologic effects of ethylene dibromide in the mouse and their modulation by the estrous cycle.

Estrous cycle modulation of immunologic sensitivity to ethylene dibromide (EDB) was studied in addition to toxicologic end points. Female B6C3F1 mice were injected intragastrically with 31.25, 62.5, or 125 mg/kg EDB for 5 days a week for 12 weeks. Vaginal smears determined the estrous cycle. At 125 mg/kg there were decreases in hemoglobin and hematocrit and longer estrous cycles (5.5 vs 4.3 days, p = 0.006), and increases in cholesterol, triglycerides, total protein, and albumin. The negative dose response seen for T- and B-cell mitogenesis around metestrus was absent for mice near estrus. The high dose of EDB prolonged intervals between estrus, was immunotoxic and immunosuppressive.