Extended Data Fig. 10: Deacetylated anti-Lm antibodies protect via CD22-mediated suppression of B cell IL-10 production.

(a) Representative FACS plots showing GFP expression by B220⁺IgM⁺CD5⁺ splenocytes 72 hours after virulent Lm infection in neonatal IL10-eGFP reporter mice administered vSera or pSera along with anti-CD22 neutralizing or isotype control antibodies, compared with no infection control mice. (b) Representative FACS plots showing GFP expression by B220⁺IgM⁺CD5⁺ splenocytes from IL10-eGFP reporter mice stimulated with UV-inactivated Lm for 20 hours in the presence of vIgG or pIgG plus anti-CD22 neutralizing antibody or isotype control. (c) GFP expression by B220⁺IgM⁺CD5⁺ splenocytes from IL10-eGFP reporter mice after UV-Lm stimulation plus anti-CD22 neutralizing antibody or isotype control without anti-Lm IgG. (d) GFP expression by B220⁺IgM⁺CD5⁺ splenocytes from IL10-eGFP reporter mice stimulated with the TLR2 agonist Pam3CSK4 in the presence of vIgG or pIgG. (e) Anti-Lm antibody titers in neonatal mice transferred vSera or sera from naive mice along with anti-IL10 receptor blocking or isotype control antibodies. (f) Model of pregnancy-induced deacetylation of anti-Lm antibodies that unleash their protective function by overriding IL-10 production by B10 cells via CD22. Each symbol represents the data from cells in an individual well under unique stimulation conditions combined from 4-5 independent experiments (c, d), or individual mice (e) with graphs showing data combined from at least 2 independent experiments with 3-5 mice per group per experiment. Bar, mean ± standard error. P values between key groups are shown as determined by one-way ANOVA adjusting for multiple comparisons.