IL21 and Huntington disease: Strikingly, induction of IgG+ class switched B cells was strongly reduced (IgG: 2.9% in P1 and P2, 2.6% in P5 vs 15.5% in HD in CD40L + IL-4/IL-21 cultures), while the generation of IgA+ switched B-cells was essentially abolished (IgA: 0.2% in P1 and P2 and P5 vs 4% in HD) by the AICDA L189X variant (Fig. 3b, right panel).