In John's Gospel, when Jesus died on the cross, He cried out with a loud voice and handed over His Spirit. He handed over the Holy Spirit to the Church. But they had not received the fullness of the Spirit and it would be this night that they would receive the Holy Spirit in a new and special way. But here they receive the Holy Spirit in a very special way this night. The next thing that we see in this narrative of John is the way in which he speaks of the disciples.
Disciples are followers.
But these were more than just the ten. After all, there were only ten at this point. Thomas was - we don't know where. Because of Thomas' absence, Jesus appeared to him a week later to deal with him in matters of faith. But there were more than just these ten there.