17beta-Estradiol increases the number of effector memory CD8+ lymphocytes in mice with contact hypersensitivity and among cultured splenocytes.

To determine how estrogen exacerbates allergies, the effects of 17beta-estradiol (E2) on lymphocyte proliferation were investigated. BALB/c mice were ovariectomized, administered 3.2 microg E2, and sensitized with 50 microL 4-ethoxymethylene-2-phenyl-2-oxazolin-5-one. After 7 days, their spleens were excised and flow cytometrically analyzed. The CD8(+)CD45RA(-)CCR7(-) cell-to-CD8(+) cell ratio in the spleen was greater in the E2-administered mice than in the controls. Splenocytes were cultured under concanavalin A stimulation, with or without E2. After 4 days, the above ratio was greater in the case of E2-treated splenocytes. E2 increases the number of effector memory CD8(+) lymphocytes during sensitization in contact hypersensitivity.