In vitro effects of prepartum concentrations of oestradiol-17 beta on cell-mediated immunity and phagocytosis by porcine leukocytes.

The in vitro effect of oestradiol-17 beta (Oe2) on cell-mediated immunity (CMI) and phagocytosis by leukocytes obtained from ten and eight sows, respectively, was studied. The concentrations of Oe2 used were 300 pmol/l and 3000 pmol/l, to reflect a low and a high prepartum concentration of the hormone. The CMI was measured by lymphocyte proliferation (LP) tests performed on whole blood and purified mononuclear cells (MNC) and by estimation of the production of interleukin-2 (IL-2) in the latter type of culture. In the whole blood LP test, the mitotic response to concanavalin A (Con A) was increased by 29% (P less than or equal to 0.05) when the Oe2 concentration was 300 pmol/l. The higher concentration of Oe2 (3000 pmol/l) increased the amount of IL-2 in supernatants from Con A-stimulated MNC by 17% (P less than or equal to 0.05). The phagocytic function of polymorphonuclear leukocytes was determined in a chemiluminescence assay. In this assay, the maximal rate of phagocytosis was reduced by 12% (P less than or equal to 0.01) and the area under the curve by 10% (P less than or equal to 0.05) at an Oe2 concentration of 3000 pmol/l. The results show that prepartum concentrations of Oe2 can promote CMI in vitro, but weaken phagocytosis by porcine leukocytes.