The effects of oestradiol and the oestrogen receptor antagonist ICI 182,780 were investigated on the DTH index, serum IgG and IgM levels and spleen weight in female BALB/c and MRL/MP-lpr/lpr mice. At six weeks, the mice were ovariectomised, and one week later, over a four-week period, given biweekly s.c. doses of (i) 5 mul of olive oil, or (ii) 5 mul of oil containing 3.2 mug of 17 beta -oestradiol (E2), or (iii) 5 mul of oil containing (3.2 mul of E2 + ICI 182,780, at a dose of 30 mg/kg), or (iv) the same dose of ICI 182,780 alone. E2 significantly raised the DTH index in BALB/c mice; this effect was prevented if ICI 182,780 was included in the injection. The DTH index in MRL mice was unaffected by any of the treatments. All steroid treatments raised serum IgG levels in BALB/c mice, but those in sera of MRL were unaffected and were significantly higher than those measured in BALB/c mice. ICI 182,780 depressed IgM in BALB/c mice, while all steroid treatments increased IgM in MRL mice. ICI 182,780 depressed spleen weights in both strains. Oestrogen may influence B cell function through ICI 182,780-sensitive receptors, and ICI 182,780 may have agonist actions on the immune system. (200 words)
