• Monocyte;
  • lymphocyte;
  • granulosa;
  • progesterone;
  • porcine

ABSTRACT: The objectives of this study were 1) to determine the influence of lymphocytes and monocytes on progesterone secretion by porcine granulosa cells in culture, and 2) to compare the responses of granulosa cells obtained from small versus large follicles. Granulosa cells were cocultured with lymphocytes, monocytes, and unfractionated mononuclear cells in serum-free culture medium. Progesterone content of media and cellular DNA were determined after 6, 12, and 24 hrs of culture. Progesterone production by granulosa cells alone or in coculture with erythrocytes increased (P < .001) up to 12 hrs and plateaued thereafter. Cells from large follicles produced approximately two-fold (P < .01) more progesterone as compared to those isolated from small follicles. Cell numbers, as indicated by DNA, did not change with time in any of the cultures. Lymphocytes stimulated (P < .05) progesterone production by granulosa cells from large follicles but not from small follicles. Similar results were seen when unfractionated mononuclear cells were co-cultured with granulosa cells. Monocytes stimulated progesterone production by granulosa cells from both large and small follicles. Lymphocytes and monocytes influence steroid secretion by granulosa cells in the pig in vitro. These effects are not mediated through cell proliferation and are influenced by follicle size.