Those who partake are called by God. They are Anointed by Jehovah's spirit. The Apostles were called by God through his son Jesus Christ. Jesus who was anointed by God personally chose the twelve to be his Apostles and heirs to the throne of Heaven. The others were chosen by God and Jesus from Heaven by means of the Holy Spirit. Paul was directly chosen by Jesus to become a heir to the throne of Heaven. He did not participate in the pouring out of the Holy Spirit on the congregation at that time.
John 15:14-17, John 17:6-10
So in conclusion only those called by God and Jesus are allowed to partake of the emblems not the entire congregation.