Objection 1. It seems that Christ did not give His body to Judas. Because, as we read (Matthew 26:29), our Lord, after giving His body and blood to the disciples, said to them: "I will not drink from henceforth of this fruit of the vine, until that day when I shall drink it with you new in the kingdom of My Father." From this it appears that those to whom He had given His body and blood were to drink of it again with Him. But Judas did not drink of it afterwards with Him. Therefore he did not receive Christ's body and blood with the other disciples.
Objection 2. Further, what the Lord commanded, He Himself fulfilled, as is said in Acts 1:1: "Jesus began to do and to teach." But He gave the command (Matthew 7:6): "Give not that which is holy to dogs." Therefore, knowing Judas to be a sinner, seemingly He did not give him His body and blood.
Objection 3. Further, it is distinctly related (John 13:26) that Christ gave dipped bread to Judas. Consequently, if He gave His body to him, it appears that He gave it him in the morsel, especially since we read (John 13:26) that "after the morsel, Satan entered into him." And on this passage Augustine says (Tract. lxii in Joan.): "From this we learn how we should beware of receiving a good thing in an evil way... For if he be 'chastised' who does 'not discern,' i.e. distinguish, the body of the Lord from other meats, how must he be 'condemned' who, feigning himself a friend, comes to His table a foe?" But (Judas) did not receive our Lord's body with the dipped morsel; thus Augustine commenting on John 13:26, "When He had dipped the bread, He gave it to Judas, the son of Simon the Iscariot [Vulgate: 'to Judas Iscariot, the son of Simon," says (Tract. lxii in Joan.): "Judas did not receive Christ's body then, as some think who read carelessly." Therefore it seems that Judas did not receive the body of Christ.
On the contrary, Chrysostom says (Hom. lxxxii in Matth.): "Judas was not converted while partaking of the sacred mysteries: hence on both sides his crime becomes the more heinous, both because imbued with such a purpose he approached the mysteries, and because he became none the better for approaching, neither from fear, nor from the benefit received, nor from the honor conferred on him."
I answer that, Hilary, in commenting on Matthew 26:17, held that Christ did not give His body and blood to Judas. And this would have been quite proper, if the malice of Judas be considered. But since Christ was to serve us as a pattern of justice, it was not in keeping with His teaching authority to sever Judas, a hidden sinner, from Communion with the others without an accuser and evident proof. lest the Church's prelates might have an example for doing the like, and lest Judas himself being exasperated might take occasion of sinning. Therefore, it remains to be said that Judas received our Lord's body and blood with the other disciples, as Dionysius says (Eccl. Hier. iii), and Augustine (Tract. lxii in Joan.).
Reply to Objection 1. This is Hilary's argument, to show that Judas did not receive Christ's body. But it is not cogent; because Christ is speaking to the disciples, from whose company Judas separated himself: and it was not Christ that excluded him. Therefore Christ for His part drinks the wine even with Judas in the kingdom of God; but Judas himself repudiated this banquet.
Reply to Objection 2. The wickedness of Judas was known to Christ as God; but it was unknown to Him, after the manner in which men know it. Consequently, Christ did not repel Judas from Communion; so as to furnish an example that such secret sinners are not to be repelled by other priests.
Reply to Objection 3. Without any doubt Judas did not receive Christ's body in the dipped bread; he received mere bread. Yet as Augustine observes (Tract. lxii in Joan.), "perchance the feigning of Judas is denoted by the dipping of the bread; just as some things are dipped to be dyed. If, however, the dipping signifies here anything good" (for instance, the sweetness of the Divine goodness, since bread is rendered more savory by being dipped), "then, not undeservedly, did condemnation follow his ingratitude for that same good." And owing to that ingratitude, "what is good became evil to him, as happens to them who receive Christ's body unworthily."
And as Augustine says (Tract. lxii in Joan.), "it must be understood that our Lord had already distributed the sacrament of His body and blood to all His disciples, among whom was Judas also, as Luke narrates: and after that, we came to this, where, according to the relation of John, our Lord, by dipping and handing the morsel, does most openly declare His betrayer."
Source: Summa Theologica (New Advent)