PRTN3 and systemic lupus erythematosus: Similar to the reduction in class-switched antibodies we showed in C57BL/6 mice and autoantibodies in lupus-prone MRL/Faslpr/lpr mice (Figures 1–, 3) (25), butyrate treatment reduced total and NP4-binding IgG1 in AicdacreEsr1+/+ mice.