Fig. 3: Targeting of anti-MuSK B cells through the BCR with MuSK-CAART demonstrates comparable efficacy as anti-CD19 CAR-mediated cytolysis, in the presence or absence of soluble anti-MuSK antibody.
a,b, Total flux (p s−1, photons per second) after injection of 1:1:1:1 mixed 13-3B5/3-28/24C10/192-8 or 13-3B5/3-28/24C10/4A3 (anti-Ig1/Ig2/Ig3/Fz) (a), 13-3B5 (anti-Ig1) or 13-3B5* (anti-Ig1, antibody-secreting) Nalm-6 cells (b), followed 4 days later by treatment with 1 × 107 NTD-T (black, n = 5), CART-19 (blue, n = 5) or MuSK-CAART (red, n = 5). Bioluminescence images appear in Extended Data Fig. 6a. One-way ANOVA with the Holm–Sidak test for multiple comparisons, day 23. c,d, Splenocytes were analyzed on days 24 or 25 after target cell injection for CD3+ T cell frequency (c) (median values are indicated; Kruskal–Wallis test with Dunnett’s test for multiple comparisons), and percentage of MuSK-CAAR+ and anti-CD19 CAR+ T cells relative to the infusion product (IP) (d). Error bars indicate mean ± s.e.m. One-sample t-test. Two MuSK-CAART-treated mice in Nalm-6 13-3B5/13-3B5* and two CART-19-treated mice in Nalm-6 13-3B5 experiments that were used for long-term follow-up were excluded from analysis. e, Anti-MuSK antibody titer in blood samples was measured on days 5 and 15 after target cell injection and quantitated relative to a 13-3B5 IgG4 mAb standard. Two-way ANOVA with Dunnett’s test for multiple comparisons. f, Direct immunofluorescence analysis of diaphragm muscle harvested on day 25, stained with antihuman IgG to detect 13-3B5 IgG4 binding to MuSK on the muscle cell surface. Diaphragms from 13-3B5/NTD-T-treated mice served as a negative control. Scale bar, 50 µm. Representative images are shown from two independent staining experiments. NS, P > 0.05; *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.
