Does the use of "a witness" in the context of immunized testimony constitute self-incrimination?

¹⁰² For clarity, we have taken the liberty of emending the Government's original use of "a witness" to "that defendant," because selfincrimination, by definition, is only a concern when the defendant was the witness.

¹⁰³ Id. at 123.

¹⁰⁴ Younger v. Harris, 401 U.S. 37, 44, 91 S.Ct. 746, 27 L.Ed.2d 669 (1971).

¹⁰⁵ See United States v. North, 920 F.2d 940, 942 (D.C. Cir. 1990) ("[W]itnesses' exposure to immunized testimony can taint their trial testimony irrespective of the prosecution's role in the exposure."); see also 18 U.S.C. 6005.