EXPRESSION OF INTERLEUKIN-1 SYSTEM MESSENGER-RNA IN SINGLE BLASTOMERES FROM HUMAN PREIMPLANTATION EMBRYOS

Gathering knowledge about the molecular events during preimplantation development is one of the most important challenges in in-vitro fertil ization (IVF). The interleukin-1 (IL-1) system has been shown to be in timately involved in embryonic implantation. The aim of our study was to detect the major components of the IL-1 system in single blastomere s from human preimplantation embryos and to relate our findings to the further development of the biopsied embryos in vitro. Single blastome res were removed from morphologically normal embryos obtained from dip ronuclear zygotes and examined by reverse transcription (RT)-nested po lymerase chain reaction (PCR), Expression of beta-actin (external stan dard), IL-1 beta, IL-1 receptor antagonist (IL-1ra) and IL-1 receptor (IL-1R) type I mRNA were related to embryonic development and IVF outc ome. Blastomeres from 12 embryos were examined: beta-actin and IL-1R t ype I mRNA were detected in all blastomeres (100%) whereas IL-1 beta c ould be detected in only nine of the blastomeres (75%), IL-1ra was exp ressed in only two (17%) of the blastomeres and those were simultaneou sly positive for IL-1 beta. Both IL-1ra positive embryos were arrested in development before reaching blastocyst stage. Five embryos (three of them IL-1 beta mRNA positive and two IL-1 beta mRNA negative) were transferred as blastocysts; none of the transfers resulted in a pregna ncy. We postulate that embryos expressing IL-1ra mRNA in a detectable amount appear more likely to be arrested in early developmental stages .