Effects of Oestradiol and the Oestrogen Antagonist lei 182,780 on the Delayed Type Hypersensitivity (DTH) Index and on Serum Levels of lgM and lgG in Ovariectomised Balb/C and MRL/Mp-Lpr/Lpr Mice, a Model of Systemic Lupus Erythematosus (SLE).

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 MRLIMP-Ipr/lpr mice. At six weeks, the mice were ovariectomisecl, and one week later, over a four-week period, given biweekly s.c. doses of (i) 5μJ l of oli ve oil, or (i i) 5 μ1 of oil containing 3.2 μg of 17β-oestradiol (E2), or (iii) 5 μl of oil containing (3.2 μl 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 injectio n . The DTH index in MRL mice was unaffected by any of the treatments. All steroid u·eatments raised serum IgG levels in BALB/c mice, but those in sera of MRL were un affected and were significantly higher than those measured in BALB/c mice . ICI 182,780 depressed TgM in BALB/c mice, while all steroidtreatments increased JgM in MRL mice. ICI 182,780 de pressed spleen weights in both strains. Oes u·ogen may influence Bcell functiontlu·ough ICI 182,780-se nsitive receptors, and ICI 182,780 may have agonist actions on the immune system. (200 words).