Administration of thymocytes derived from nonpregnant mice induces an endometrial receptive stage and leukaemia inhibitory factor expression in the uterus
K. Fujita et al., Administration of thymocytes derived from nonpregnant mice induces an endometrial receptive stage and leukaemia inhibitory factor expression in the uterus, HUM REPR, 13(10), 1998, pp. 2888-2894
We have previously reported that intravenous administration of splenocytes
prepared from mice in the early stages of pregnancy promoted embryo implant
ation in pseudopregnant mice, Since a T-lymphocyte-rich, but not a monocyte
-rich preparation from splenocytes enhanced embryo implantation, similar ef
fects of thymocytes from non-pregnant mice on implantation were examined in
this study, Thymocytes were prepared from immature 21 day old ICR female m
ice and the supernatant of a thymocyte suspension (Th-sup) was used as the
control, Thymocytes or Th-sup were injected into the caudal vein of recipie
nt mice on pseudopregnancy day 2, and blastocysts were transferred into the
endometrial lumen. The implantation rates per recipient were significantly
higher in the thymocyte-treated group. ICR mice were then oophorectomized
on pseudopregnancy day 3, After 3-day progesterone supplementation, blastoc
ysts mere transferred with intravenous injection of thymocytes or Th-sup. U
nder progesterone supplementation, successful implantations were observed i
n the thymocyte-treated group, but not in the Th-sup-treated group. Reverse
transcriptase-polymerase chain reaction analysis revealed that mRNA expres
sion of leukaemia inhibitory factor in the uterus was induced by thymocyte
administration, but not by Th-sup, Thymocytes mere divided into two populat
ions, CD4(+/-)CD8(-) group and CD4(-)CD8(+/-) group, by separation columns.
On pseudopregnancy day 2, the separated thymocytes in each group or their
supernatant mere injected into the endometrial stroma of the recipient mice
, and blastocysts were transferred into the endometriaI lumen, The administ
ration of CD4(+/-) CD8(-) lymphocytes significantly promoted implantation r
ates, but no effect was observed in the CD4(-) CD8(+/-) group, These findin
gs showed that thymocytes, especially CD4-positive lymphocytes, facilitate
embryo implantation, probably by regulating endometrial differentiation.