PRESENCE OF LEUKEMIA INHIBITORY FACTOR AND INTERLEUKIN-6 IN PORCINE UTERINE SECRETIONS PRIOR TO CONCEPTUS ATTACHMENT

Leukaemia inhibitory factor (LIF) plays an important role in embryo de velopment and implantation. We detected peak LIF activity in porcine u terine luminal fluids (ULF) at day 12 of gestation and during day 7 an d 13 of the oestrous cycle. A radio-receptor competition assay showed the presence of a molecule in ULF specifically binding to human LIF re ceptor (LIF-R). LIF activity was partially neutralized by anti-human L IF antibody. Interleukin-6 (IL-6) activity was detected in ULF through out the oestrous cycle and pre-implantation period. An anti-murine alp ha chain (gp80) of IL-6 receptor (IL-6R) specifically neutralized this activity. LIF and IL-6 mRNA were only detected in day 11 endometrium. The presence of LIF or IL-6 in the uterine cavity has not been previo usly reported. Our results extend LIF production by endometrium during the oestrous cycle and pre-implantation period to another mammalian s pecies other than mouse.